BYGL Weekly News for August 5, 2019

The following articles were compiled during the last 7 days by members of the Extension, Nursery, Landscape, Turf (ENLT) team to benefit those who are managing a commercial nursery, garden center, or landscape business or someone who just wants to keep their yard looking good all summer.  Access the BYGL website for additional information on other seasonal topics at: http://bygl.osu.edu

 

To receive immediate email notifications when articles are published by the BYGL writers. Send an email to bygl-alert@lists.osu.edu using the phrase “Subscribe to BYGL ALERTS” in the subject line. 

 

For more pictures and information, click on the article titles.  To contact the authors, click on their names.

 

 

Vultures

Authors Joe Boggs

Published on August 3, 2019

 

 

I’ve long had a fascination with Turkey Vultures (Cathartes aura) starting when I was a kid in West Virginia.  I liked to lay on the ground observing these avian gliders catching thermal updrafts to stay aloft for hours without flapping their wings.  This stopped when one of my uncles observed that I looked dead.

 

Of course, I wouldn’t have sprung to my feet so quickly had I known then what I know now about turkey vultures.  While it’s true that turkey vultures are carrion feeders, they rely on more than just their excellent eyesight to locate an expired meal.  They also have an exceptional sense of smell.

 

During a recent drive in southern Ohio, I came across another type of vulture:  the Black Vulture (Coragyps atratus).  These vultures are not as large as turkey vultures; however, they are still big birds.  Their name comes from their black, featherless heads.  Only the juveniles have feathers on their heads.  Turkey vultures have featherless red heads which makes them resemble turkeys.

 

Black vultures have excellent eyesight but lack the olfactory capabilities of turkey vultures.  In fact, freeloading black vultures often stay close to turkey vultures letting their carrion-seeking kin locate smelly, dead meals.

 

Turkey vultures have silver-gray flight feathers beneath their wings.  Although I don’t have a picture of a black vulture in flight, the feathers beneath their wings are entirely black except for the base of the flight feathers at the tips of the wings which are silvery-white.

 

Turkey vultures live year-round throughout South America north into the middle part of North America.  Their range extends into southern Canada during the summer.  Historically, black vultures shared a large portion of this range, but they did not migrate out of the southern U.S. states.  However, that has gradually changed.  Over the past several decades, black vultures have found their way into our state as well as Kentucky and Illinois.

 

My uncle’s tongue-in-cheek warning may have carried more weight had turkey vultures shared the West Virginia skies with black vultures.  That’s because black vultures will kill things.  While they are primarily scavengers, black vultures are known to kill newborn calves, lambs, and small pets.  However, their handiwork may be blamed on other predators, particularly where they have just moved into a new area.  Prevention is not straight forward because both turkey and black vultures are protected by the Migratory Bird Treaty Act of 1918 and can only be killed under a Migratory Bird Depredation Permit through the U.S. Fish and Wildlife Service.  It is legal to harass the birds.  Perhaps laying in wait on the ground has some value after all …

 

What’s in a Name?

I grew up calling turkey vultures “buzzards.”  However, in preparing this Alert, I came across numerous esteemed ornithological resources that failed to provide information on buzzards.  Just try typing “buzzard” into the website search engines for the Cornell Lab of Ornithology or the Audubon Guide to North American Birds.

 

I eventually discovered that bird people reserve the “buzzard” name for several species of birds of prey that belong to the genus Buteoand are found in Europe and Asia.  What?

 

Although the taxonomy is still being sorted, in general, vultures are divided into two types grouped in the order Accipitriformes.  New World vultures belong to the family Cathartidae and include seven species found in North, Central, and South America.  Two of the species are the turkey and black vultures.

 

Old World vultures belong to the family Accipitridae which includes 16 species.  All have “vulture” in their common name and are found in Europe, Asia, and Africa.  The family also includes eagles, hawks, and buzzards.  The eagles and hawks are found throughout the world and include our own Bald Eagle (Haliaeetus leucocephalus).  However, the buzzards are only found in Europe and Asia.  Just try telling that to the good people of Hinckley.

 

 

 

Stink Bug Hunters Provide a Landscape Twofer

Authors Joe Boggs

Published on August 1, 2019

 

 

I attended a meeting last Thursday on plant pollinators at the Cincinnati Zoo and Botanical Garden (CZBG).  One focus was on managing pests by increasing the abundance and diversity of flowering plants in a landscape.

 

Many beneficial insects wear two hats by serving as both plant pollinators and enemies of other insects.  It’s likely one reason the CZBG rarely needs to deal with significant plant pest problems is because the CZBG’s widely diverse landscape encompasses a smorgasbord of flowering plants including trees and shrubs as well as annuals and herbaceous perennials.  They make no insecticide applications because they don’t need to apply this pest management tool; they’re using another one.

 

After the meeting, Steve Foltz (Horticulture Director) showed me an expanse of sand that was literally buzzing with a perfect example.  Small wasps were busily digging burrows.  They were female Bicyrtes quadrifasciatus, a species with no approved common name.  However, the wasps are generally referred to as the Stink Bug Hunter (SBH) based on their preferred prey. They are arch enemies of stink bugs including the non-native invasive Brown Marmorated Stink Bugs (BMSB) (Halyomorpha halys)

 

SBH belongs to the family Crabronidae which also includes the Eastern Cicada Killer (Sphecius speciosus).  However, they are only about 3/4ths the size of cicada killers.  Both wasps have conspicuous cream-colored abdominal markings on a black background.  The SBH females have four abdominal stripes which are referenced in their specific epithet, quadrifasciatus, means “four banded.”

 

As with the cicada killers, SBH is considered a “solitary wasp” even though they typically nest in large numbers over relatively small areas with their collection of burrows often referred to as “colonies.”  The colonies evolve because the females of both species have specific nesting requirements.  It is also speculated that large numbers of females gathered in one location helps males to find them which increases the chances all of the females will be mated.

 

SBH digs their burrows almost exclusively in sand which is why they are grouped within the Sand Wasp tribe, Bembicini.  They are fast diggers and look like tiny dogs shoveling sand with their front legs backward between their hind legs.  A close examination will reveal that their first and second pairs of legs are slightly curved inward to support digging as well as grasping their prey.

 

SBH females may attack different types of True Bugs (suborder Heteroptera) including leaf-footed bugs (family Coreidae).  However, it’s their overarching predilection for stink bugs (family Pentatomidae) that makes them such an important enemy of BMSB.

 

The females tend to select stink bug nymphs, possibly owing to their smaller size compared to the adults.  She grabs and stings the nymph to paralyze it, then she carries her prize back to her burrow and stuffs it inside.  After she has provisioned her burrow with several helpless nymphs, she lays a single egg, leaves the burrow and seals the entrance.  It’s an ingenious way to get around the lack of refrigeration.  The immobilized nymphs remain alive (perhaps horribly aware?) to serve as fresh meat for the soon-to-hatch, grub-like wasp larva.

 

A survey of native biocontrol agents of BMSB conducted in 2011 by Penn State researchers in fruit orchards and surrounding habitat revealed that 96% of the stink bugs found in SBH burrows were BMSB nymphs.  While the survey was conducted during a “peak year” in BMSB numbers in PA and in locations with concentrated bug populations (orchards), the results still point to these sand wasps as being an important bio-ally.

 

What about the risk of getting stung?  Like cicada killers and the vast majority of solitary wasps, sand wasps were not aggressive.  In fact, as I strolled through the SBH colony at the CZBG to take pictures, the wasps never displayed any type of threatening behavior despite my close-in photo shoots.

 

Attracting these wasps to landscapes may be an important method for decreasing BMSB populations as well as a number of other stink bugs.  The adults feed on nectar; they are pollinators.  Adding “pollinator plants” to landscapes provides significant support for these and other bio-allies that can play a critical role in suppressing pests.  “Butterfly Gardens” and “Pollinator Gardens” should be appreciated beyond their support of pollinators; they’re also pest management tools.

 

 

 

 

Bladdernut Slug Sawfly Conundrum

Authors Joe Boggs

Published on August 1, 2019

 

 

I’ve observed slug-type sawfly larvae skeletonizing leaves on the same American bladdernut (Staphylea trifolia) trees growing in a southwest Ohio landscape in 2015, 2017, and again late last week.  I’ve concluded they must cause little harm to the overall health of their bladdernut host because the trees continue to flourish despite providing some great photo ops of the sawfly larvae and their damage over the years!

 

The odd thing about these sawflies is that they are the spitting image of Scarlet Oak Sawfly (Caliroa quercuscoccineae) which is sometimes called the scarlet oak slug sawfly or just oak slug sawfly.  The “slug” in the common names are based on their elongated unsegmented bodies and a covering of mucoid-like slime that presumably helps them stick to the undersides of leaves.  You can read more about oak slug sawflies in an Alert posted in early June titled, “Be Alert to Scarlet Oak Sawfly”:

https://bygl.osu.edu/node/1298

 

However, I have never found host records that indicate scarlet oak sawfly feeds on anything other than its namesake host as well as a few other oaks.  I’ve also never found information on a species of sawfly that feeds on bladdernut.  This may be undescribed slug sawfly species that is specific to bladdernut.  If so, the common name of “Bladdernut Slug Sawfly” seems appropriate.

 

Although bladdernut slug sawfly larvae look like the slimy scarlet oak sawfly larvae, their feeding behavior is somewhat different and their ultimate leaf damage is very different.  Scarlet oak sawfly larvae skeletonize leaves by munching side-by-side across the lower leaf surface consuming everything except the leaf veins and upper leaf epidermis.  This produces a windowpane effect that fans out as larval feeding progresses.

 

Bladdernut slug sawfly larvae also feed on the lower leaf surface and consume everything except the leaf veins and upper leaf epidermis.  However, their feeding behavior is much less organized.  Rather than marching side-by-side across the lower leaf surface, bladdernut sawfly larvae crawl about in a more casual fashion to produce random window-like skeletonizing.

 

Initially, the leaves have a faded, whitish appearance.  Ultimately, the window-like epidermis dries and drops from the leaf to produce large holes, or the entire bladdernut leaf simply turns brown and becomes paper-like.

 

Scarlet oak sawfly has 2 – 3 distinct generations per season in Ohio with the number varying between the northern and southern parts of the state.  The generations do not overlap and larval development appears to be relatively synchronized; it’s rare to find larvae that aren’t equal aged.

 

The opposite is true with bladdernut slug sawfly.  It’s common to find a range of instar stages feeding on the same leaf.  I’ve photographed what appear to be late-instar larvae feeding on one leaf and obviously first-instar larvae feeding on another nearby leaf.  I’m not certain if this represents overlapping generations or if egg hatch commonly occurs over an extended period.  However, because I’ve observed larvae feeding from early June to early September, it reasonable to assume that this sawfly has multiple generations per season.

 

 

 

 

Sedum Flea Beetle Conundrum

Authors Joe Boggs

Published on August 1, 2019

 

 

We teach the importance of identifying a pest in order to develop an effective pest management plan.  An accurate ID leads to learning about the pest’s lifestyle including host range and numbers of generations per season.  Occasionally, a significant insect pest somehow continues to fly below the radar of insect taxonomists.

 

Such is the case with the “Sedum Flea Beetle.”  I’m using quotes because I’ve never found a reference assigning both a scientific as well as the common name to the beetle.  This is my own made-up common name, but it captures the host range that I’ve observed thus far.

 

Purists will recognize that I’m bending plant taxonomy rules a bit by ignoring the fact that the genus Sedum no longer applies to many stonecrop plants used in landscapes.  However, gardeners commonly refer to stonecrops as sedum whether the plants belong to the Sedum or Hylotelephium genera.

 

I first came across the beetle in mid-October, 2011, after receiving a phone call from a homeowner in eastern Cincinnati who said brightly colored beetles were destroying her “sedum.”  I visited and found that a flea beetle was doing so much damage the only way I could identify the defoliated plants was through a plant tag; it was Hylotelephium telephium ‘Autumn Joy’ (family Crassulaceae).  There was little joy in the appearance of the landscape planting.

 

Last year, I received a report in mid-June that the same beetle was damaging ‘Autumn Joy’ and ‘Munstead Red’ in a landscape in Dayton.  I visited in mid-June and found both adults as well as larvae.  This season I’ve gotten e-mail messages with pictures showing the beetle on unidentified stonecrop plants in a suburb of Dayton and in western Hamilton County.

 

The reports and observations I’ve made thus far; in mid-June and mid-October, strongly indicates the sedum flea beetle has at least two generations, if not more.  This may also explain why the plants I observed in October were so heavily damaged.  The population along with the damage escalated with each succeeding generation.

 

The sedum flea beetle looks very similar to the Passionflower Flea Beetle (Disonycha discoidea, family Chrysomelidae).  You can see some good pictures of this beetle posted on BugGuide by clicking on this hotlink:

https://bugguide.net/node/view/4521.

 

However, the authors of Host Plants of Leaf Beetle Species Occurring in the United States and Canada (Clark et al. 2004) note that the passionflower flea beetle only feeds on passionflowers (family Passifloraceae) including Passiflora incarnata and P. lutea.  Neither Sedum nor Hylotelephium is listed as hosts for any of the 31 flea beetle species in the Disonycha genus.

 

In fact, the home gardener in western Hamilton County noted she is only finding the beetles on sedum.  She has not found them feeding on a passionflower growing in her landscape.

 

Based on reports I’ve gotten thus far, I’ve concluded this beetle has the potential to cause significant damage to various stonecrop plants.  I don’t know if the recent reports were plants belonging to the Sedum or Hylotelephium genera.

 

Please Report

I’d like to learn more about this beetle as well as its host range.  If you see the sedum flea beetle, please drop me a note with your location and contact information.  Also, if possible, include the identity of the host plant (is it Sedum or Hylotelephium).  Just click on my name at the top of this Alert and then click on my e-mail address.

 

 

 

Pavement Ants Have Stingers?

Authors Joe Boggs

Published on July 30, 2019

 

 

I received a phone call last Friday from a homeowner in Reynoldsburg, OH, who reported that his neighbor had been stung by a horde of aggressive ants.  He called because he had seen a BYGL Alert posted last year on Asian Needle Ants (Brachyponera chinensis) in southwest Ohio (see “Non-Native Stinging Ant Confirmed in Southwest Ohio,” January 26, 2018:  https://bygl.osu.edu/node/970)

 

Given the homeowner’s close proximity to our Ohio State University C. Wayne Ellett Plant and Pest Diagnostic Clinic (PPDC) located in the Ohio Department of Agriculture’s complex, I urged that he drop specimens off at the Clinic for a positive identification.  Ever since the discovery of needle ants in my neck of the woods, I and others have been interested to learn if this aggressive stinging ant had spread to other areas of the state.

 

Dave Shetlar (Professor Emeritus, OSU Entomology) made the identification of the ants and here is what he wrote in the Clinic report:

 

About five workers of the common pavement ant (Hymenoptera: Formicidae: Tetramorium caespitum) were found, still alive. The client was wondering if these were the Asian needle ants because the ants had stung during a recent encounter. Pavement ants are easily recognized by the presence of numerous furrows present on the surface of the exoskeleton of the head and thorax plus they have two nodes. The Asian needle ants have a smooth exoskeleton surface and one prominent node. Pavement ant workers have a small stinger which is capable of penetrating human skin where it is thin. Stings are normally considered to be inconsequential, but like all venoms, individual people may have severe reactions to the foreign proteins present in the venom. Such reactions can result in intense burning, itching and even the formation of a small blister. If these develop, frequent washing and application of anti-itching creams can help avoid scratching and secondary infections.

 

I’ve long been aware of pavement ants.  This non-native species was introduced to the U.S. from Europe over 100 years ago and has risen to become one of the most common ants found in Ohio, particularly in urban areas.

 

This pugnacious ant is well-known for its bare-tarsal brawls.  Battles between competing colonies may occur as a single, massive, swirling clash, or as a serious of smaller pitched skirmishes with constantly shifting battle lines.  I’ve frequently had a ringside seat to one of these ant melees.

 

However, I never knew that pavement ants have stingers!

 

 

 

Phytoplasmas, Elm Yellows, and the Complete Diagnostic Process

Authors Joe Boggs

Published on July 30, 2019

 

 

I posted an Alert yesterday that stated Elm Yellows (EY) has been confirmed by Ohio State University C. Wayne Ellett Plant and Pest Diagnostic Clinic (PPDC) in a park in Greater Cincinnati.  This not correct.

 

The PPDC only detected a phytoplasma in an elm sample.  However, more work is being done by the Clinic involving DNA sequencing to learn the true identity of the phytoplasma; whether or not it’s actually ‘Candidatus Phytoplasma ulmi’ which is the bacterium behind the disease known as EY.  I jumped the gun.

 

A Cautionary Tale

Phytoplasmas are small highly specialized bacteria that appear to only infect plants.  However, finding a phytoplasma in a host known to be susceptible to a particular phytoplasma-induced disease does not necessarily mean the detected phytoplasma is causing the disease.  In other words, finding a phytoplasma in American elm may not mean it’s the phytoplasma that causes EY.

 

What if it’s an undescribed phytoplasma?  What if it’s producing an undocumented disease?  What if it’s the phytoplasma that’s responsible for EY, but it’s presenting uncharacteristic symptoms?  These points are very important relative to learning the truth of what’s actually going on; a truth the PPDC is still in the process of pursuing.

 

In my imprudent BYGL Alert, I noted that the symptoms on the American elms were “atypical.”  Instead of the leaves rapidly turning an intense shade of lemon-yellow to yellowish-orange, the symptom that gives EY its name, there was minimal yellowing on the leaves on the tree that tested positive for a phytoplasma.  The leaves rapidly wilted throughout the canopy and the entire canopy defoliated over just a few days.

 

I broke my own golden diagnostic rule:  do not make the symptoms fit the diagnosis, make the diagnosis fit the symptoms.

 

This is why I’m correcting my earlier report.  The PPDC is sending material for DNA sequencing.  Once the PPDC has established the complete story, we will post an Alert at the appropriate time with more complete details.

 

You can learn more about these plant pathogenic phloem-limited bacteria including the history of their discovery by reading the following paper titled, “Phytoplasmas and Phytoplasma Diseases: A Severe Threat to Agriculture”:

https://file.scirp.org/Html/4-2601437_46299.htm

 

Elm Yellows Still a Concern

Regardless of the outcome of the PPDC investigation, EY remains a concern on American elms in Ohio and elsewhere.  Here are some common indicators that an elm may be infected with the EY phytoplasma:

 

Rapid Leaf Yellowing and Defoliation:  the name “elm yellows” describes the color of the leaves on infected trees.  The color-change occurs quickly – often within a few weeks – without the leaves first wilting.  The yellowed leaves quickly drop from the trees.

 

Phloem Discoloration:  the old name for the disease was “elm phloem necrosis” which captures the essence of the infection.  The phytoplasma targets and destroys the phloem with the inner phloem becoming yellowish-brown to caramel colored and the staining extending to the surface of the xylem.  The discoloration is generally confined to the lower portion of the trunk and the lower branches.  This is because the phytoplasma first migrates to the roots causing rapid and substantial dieback of the fine feeder roots, then the main roots.  In essence, there is a “bottom-up” pattern to the infection.

 

Carefully slicing away the bark on the lower trunk or lower branches using a sharp pocket knife or a draw-knife will expose the off-colored infected phloem tissue.  A cautionary note:  elm phloem tissue will naturally become discolored by oxidation when exposed to the air.  The oxidation occurs in minutes, and mimics the discoloration caused by EY, so samples showing phloem necrosis that is suspected to be caused by EY must be fresh!

 

Wintergreen Odor:  Methyl salicylate (oil of wintergreen) is produced in the phloem tissue that is colonized by the EY phytoplasma.  Cut a section of bark to the white wood near the base of the main stem and place the sample in a sealed jar.  While the wintergreen scent is usually very faint at first, it becomes easily detectable after the sample has been held in the jar for about 3 – 4 hrs.

 

Quick Death of Trees:  Trees that appear perfectly healthy with normal twig elongation and leaf expansion early in the growing season are often dead by the end of the season.

 

CONFIRMATION:  Although the symptoms listed above provide strong evidence of EY, the only sure-fire way to know that a tree is infected (and infectious!) is to send samples to a diagnostic clinic capable of performing the appropriate tests.  Keep in mind that as illustrated by my mea culpa, it takes time for the confirmation to occur.

 

Other Elm Problems to Consider

 

Nutrient Deficiency:  The chronology of EY leaf yellowing is different from leaf chlorosis caused by nutrient deficiencies.  Typically, nutrient deficiency symptoms appear early in the season with new leaves appearing chlorotic.  Early defoliation almost never occurs.

 

Black Leaf Spot:  this fungal disease of elms produces irregular dark brown to black spots that may be slightly raised.  Heavy infections may cause leaves to yellow and drop.  However, yellowing does not occur prior to the development of the leaf spots.

 

Environmental Calamities:  Everything from poor soil conditions to drought to over and under-watering can cause American elms to collapse.  However, leaf wilting is usually a tell-tale pre-collapse symptom.

 

Vascular Wilt Diseases:  These diseases prevent water from reaching the leaves by plugging the vascular system.  Thus, vascular wilts produce noticeable and sometimes rapid leaf wilting and browning, particularly in the heat of summer, as leaves are starved for water.  Vascular wilts usually produce sectional dieback with a few branches succumbing at a time.  However, a complete collapse of the canopy is also possible.

 

American elms that are considered tolerant of DED have succumbed to DED although this is a rare occurrence.  It is speculated that trees suffering from severe stress are made more susceptible.  Verticillium wilt has long been the nemesis of American elm trees that are under stress.  Resistance to DED does not mean that elms will not suffer from branch dieback from this disease.

 

Although EY has been affecting elms for at least as long if not longer than DED, the disease has continued to appear as sporadic, highly localized outbreaks.  Often, only a few trees die even though other elms are within visual range of their demise.  Still, with the widespread reintroduction of American elms into urban landscapes, this old killer has re-emerged to present a serious threat.  If you suspect a tree is infected, act quickly by getting a confirmation.

 

 

 

Oriental Lilies Overwhelm Our Senses

Authors Erik Draper

Published on July 30, 2019

 

 

As Oriental lilies are about halfway through their “bloombastic tour”, simply walking near them causes one to be stunned visually and in the olfactories too!  After drawing in the noticeable, spicy scent wafting all around and through the air nearby the plants, it gives the feeling that breathing the regular, old normal air seem stale!  That was just one of the differences between Asiatic and Oriental lilies, which I alluded to in an earlier BYGL article this year.

 

In that article, written just about 20 days ago, I tried to give BYGLers a sense of the Oriental lilies blooms, both look and size.  I wrote “… The huge flowers are 6-9 inches across…” and just to reinforce that seemingly ridiculous size, I took a picture with a ruler for your visual enjoyment!

 

The other distinguishing characteristic beyond smell and size of the flower, is the delicate, ruffled edges on the petals of the bloom.  It is sometimes subtle, but noticeable nevertheless, if you look closely at the petal edges.

 

To make this bloom tour complete, I just wish that we had “SMELLOVISION” so that you could have the whole “bloomblastic” experience initiated by Oriental lilies!

 

 

 

Diagnostics: It’s the Environment, Man

Authors Jim Chatfield  Joe Boggs

Published on July 30, 2019

 

 

Question # 12 of our 20 Questions of Plant Problem Diagnostics is: What Is The Environmental History?”.  Here are three quick examples of the importance of this question.

 

Planetree Perserverance.  As predicted in bygl node.1305 on June 11, planetrees, especially the more susceptible American planetree (sycamore, Platanus occidentalis) that looked almost leafless due to sycamore anthracnose in May and June throughout much of Ohio, have now largely re-foliated and look fine. Cool, moist conditions during leaf emergence, so key to disease development, are past history and trees recovered nicely.

 

All Hail Honeylocust. Orange-yellow discoloration on stems, elliptical cracking on those stems. Are these fungal cankers on this backyard thornless honeylocust (Gleditsia triacanthos var. inermis ‘Imperial’) in Denver, Colorado? Not totally sure, but I suspect the smoking gun is the homeowner’s report of the environmental history of major hailstorms this spring and summer – and the “What Exactly Do You See/” question #6 of Plant Problem Diagnostics. What I exactly saw was the damage in question only occurring on – upper stem surfaces.

 

Aesculus Avoidance. On a Denver street, a reminder of home – Ohio buckeye! Leaf scorch in the hot summer heat, and some insect feeding, but – whither the Guignardia  leaf blotch fungal diseases, common on the genus Aesculus (buckeyes and horsechestnuts) and the moderately susceptible Ohio buckeye (Aesculus glabra). No Guignardia. The absence of the environmental component of the disease triangle is the key here: not a lot of wet and humid conditions in spring in Denver.

 

Diagnostics: Question Everything!

 

 

 

Bagworms Reveal Themselves!

Authors Joe Boggs

Published on July 30, 2019

 

 

This is the time of the year when Common Bagworms (Thyridopteryx ephemeraeformis) come into clear focus owing to their size and noticeable damage.  Overwintered eggs hatched in southwest Ohio in early June (see “Be Alert to Bagworms!” posted on June 6).  However, it’s amazing how well these native moth caterpillars crawl below our radar until their burgeoning appetites finally gives them away.

 

I’m speaking from personal experience.  I looked out our kitchen window this past weekend to see a hungry horde of bagworms chowing down on needles at the top of my prized Canaan fir (Abies balsamea var. phanerolepis).  How dare they!  The cheeky bagworms are no more; I have a sprayer.

 

Bagworms are so-named because the caterpillars wrap themselves in silk bags festooned with pieces of their plant host material.  The arrangement provides highly effective camouflage.

 

The bagworms spend the winter as eggs inside dead females that remain in their bags. A single female can produce 500 – 1000 eggs meaning that populations can climb rapidly.  Just a few undetected females can spawn damaging numbers of caterpillars next season.

 

Bagworms also have a habit of seeming to appear out of nowhere.  That’s partly because of their cryptic lifestyle but also because 1st instar caterpillars can produce a strand of silk to catch the wind and “balloon” to new locations.  This behavior is one of the reasons bagworms often appear on hosts that were not infested last season.

 

Bagworms can also feed on deciduous trees and shrubs as well as evergreens.  It is a common misconception that bagworms only eat evergreens.  If fact, they are called “Evergreen Bagworms” in many southern states.  However, the caterpillars may be found feeding on over 130 different species of deciduous trees and shrubs.

 

Bagworms can be controlled through physical removal as long as they are destroyed by squeezing or stepping on them once they are plucked from an infested plant.  If simply dropped to the ground, they will crawl back upon a host plant.  I would have used this method if the top of my Canaan fir wasn’t so far out of reach.  There’s a certain satisfaction with doing the “bagworm dance” to dispatch the troublesome caterpillars.

 

Early instar bagworms can be killed using products based on the naturally occurring biological insecticide Bacillus thuringiensis var. kurstaki (Btk) (e.g. Dipel, Thuricide, etc.) which preserves bio-allies.  The image below shows bagworms collected from the same host over the weekend.  The age range is not unusual and occurred because of an extended egg hatch.  However, it shows that Btk products will only be effective against a small segment of the population.  Btk is most effective on small bagworms and becomes much less effective when bags surpass 3/4″ in length.

 

The clock is also rapidly ticking down for standard insecticides to remain effective. Late instar bagworms can detect insecticide toxicants causing them to hasten pupation, but they do not die.  However, they do stop feeding which leads to the perception they were killed.  Early-pupating females produce fewer eggs, but they still produce enough to continue the infestation next season.

 

It’s important to remember that bagworms may remain attached even if the caterpillars were successfully killed with an insecticide.  They look just like bags with live caterpillars.  The deception may lead to needless repeat applications, but they can only die once.

 

 

 

Turfgrass Times, 07.26.2019

Authors Amy Stone

Published on July 30, 2019

 

 

Here is your link to the weekly video update (recorded on 07.26.2019) from the OSU Turfgrass Team. Updates are from Dr. David Gardner; Dr. Ed Nangle; Dr. Zane Raudenbush; and Joe Rimelspach this week.

 

https://vimeo.com/350360436/c659bbcbfa

 

 

 

Be Alert to Boxwood Blight

Authors Joe Boggs

Published on July 28, 2019

 

 

Boxwood Blight was recently confirmed in a private landscape in Greater Cincinnati by The Ohio State University’s C. Wayne Ellett Plant and Pest Diagnostic Clinic (PPDC).  The disease causes a severe and usually rapid decline of susceptible boxwoods.  Heavy defoliation and branch dieback can occur in a single season killing small plants.  The ornamental value of larger infected boxwoods is reduced and plants may become so stressed they succumb to secondary problems.

 

The disease is caused by the fungal plant pathogen Calonectria pseudonaviculata which was previously named Cylindrocladium pseudonaviculatum or Cylindrocladium buxicola.  The literature reports the pathogen and disease were first identified in the United Kingdom in 1994.  The current distribution includes 12 other European countries as well as western Asia and New Zealand.

 

The fungus may infect several members of the box family (Buxaceae) including Japanese spurge (Pachysandra terminalis); Allegheny spurge (P. procumbens); sweetbox (Sarcococca spp.); and of course, boxwood (Buxus spp.).  However, all boxwoods aren’t equal.  Some are highly susceptible while others are tolerant.

 

The pathogen and disease were found in Connecticut in 2011 and is now confirmed in 28 states as well as British Columbia, Ontario, and Quebec, Canada.  This is not the first time this fungal disease has been found in landscapes in Ohio.  This means that Green Industry professionals throughout Ohio must remain informed and ready to take action including confirming boxwood blight by sending samples to the PPDC.  Professionals should never rely on a “field diagnosis” to inform their actions.

 

A Boxwood Blight Case Study

Ron Rothhaas (Arbor Doctor, LLC, Cincinnati, OH) is an ISA Board Certified Master Arborist and a highly capable field diagnostician. However, rather than speculating on what might be happening in a landscape he was visiting, he confirmed what’s actually happening by sending samples to the PPDC. Ron and I will be holding a boxwood blight mini-workshop at our next Greater Cincinnati BYGLive! Diagnostic Walk-About.

 

It’s essential to separate boxwood blight from the less damaging but more common Volutella Blight produced by the fungal pathogen, Pseudonectria buxi (formerly Volutella buxi).  Plants can recover from Volutella blight; however, highly susceptible boxwoods don’t recover from boxwood blight.  Adding to the challenge, some of the samples Ron sent to the PPDC tested positive for Volutella meaning both boxwood diseases are occurring at the same time in the same planting.

 

Volutella blight is also called Pseudonectria Canker owing to the occurrence of stem cankering infections which do not occur with boxwood blight.  The leaves on cankered stems turn yellow to yellowish-brown and remain attached to the stems for an extended period of time.  Symptoms often appear in early spring and are commonly mistaken for winter injury.  Cankered stems can be removed through pruning which promotes plant recovery.

 

A signature symptom of boxwood blight is rapid defoliation.  Leaf infections may sometimes occur to produce leaf spots; however, this is not a consistent symptom.  Sometimes, leaves simply wilt, turn dark bluish-green and drop.

 

Another symptom common to boxwood blight is black streaking on the stems.  The streaks are most evident when they occur on green stem tissue.

 

It must be stressed that neither rapid defoliation nor blackened stems necessarily mean boxwoods are suffering from boxwood blight.  However, the symptoms are strong indicators that samples should be sent to a diagnostic lab such as the PPDC in Ohio.

 

Helpful Online Resources

A great deal of work has been done by universities in states where boxwood blight has been detected.  The following are a sample of some excellent university fact sheets on boxwood blight as well as Volutella blight.  They also provide in-depth management Plans:

 

Virginia Tech (VT) Best Practices

https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/PPWS/PPWS-29/PPWS-29-pdf.pdf

 

University of Kentucky (UK) – Boxwood Blight

https://plantpathology.ca.uky.edu/files/ppfs-or-w-20.pdf

 

University of Kentucky (UK) – Volutella Blight

https://plantpathology.ca.uky.edu/files/ppfs-or-w-26.pdf

 

How the Fungal Pathogen is Moved from Place-to-Place

The literature notes that the boxwood blight fungus produces heavy, sticky spores that are not carried far by the wind.  They are better suited to sticking to the feet of birds, the fur of animals, and to pruners, shears, etc.  Thus, the fungus may arrive through animal incursions, both human or otherwise.

 

This further emphasizes the need to confirm the occurrence of boxwood blight, react quickly to contain the disease, and avoid inadvertently spreading the fungus from one landscape to the next on contaminated tools, clothing, etc.  In fact, both the Virginia Tech and the University of Kentucky fact sheets provide a list of measures to prevent the site-to-site spread of the boxwood blight fungal pathogen.

 

For example, it is strongly recommended that tools used for pruning or shearing boxwoods be sanitized before moving from one group of boxwoods to another within a landscape and certainly before working on boxwoods at another site.  The Virginia Tech factsheet recommends using o-Benzyl-p-chlorophenol (e.g. Lysol Concentrate Disinfectant) mixed at a rate of 1.25 oz. / gallon.  Sodium hypochlorite (household bleach) is also recommended mixed at 1 part bleach to 9 parts water.  However, this sanitizer must be mixed fresh at frequent intervals and should be rinsed from tools to reduce damage.

 

Planting infected boxwoods is another common way for the pathogen to be spread to new landscapes.  Horticultural regulatory agencies such as the Ohio Department of Agriculture are keenly aware of boxwood blight and nursery inspectors are well-trained in detecting tell-tale symptoms.  However, the movement of plants outside of the protective regulatory shield, such as digging and moving plants from one landscape to another, presents another route for spreading the pathogen.

 

Don’t Give Up on Boxwoods

The landscape where Ron found boxwood blight includes hundreds of boxwoods; they are integral to the overall landscape design.  Indeed, boxwoods often occupy a unique profile in landscape designs based on their hard-to-match appearance.

 

Research has shown there is a range of boxwood blight susceptibility within the Buxus genus.  Some types are highly tolerant while others are highly susceptible.  This further emphasizes the need to develop and use tolerant types of boxwoods to thwart boxwood blight.

 

Research has also shown that boxwood blight can be prevented through season-long fungicidal applications made at around 14-day intervals.  However, no fungicides have been found that offer a curative option; the disease cannot be halted in plants that are infected.  This means that while fungicides may be used as part of a boxwood blight management plan, they should not be the only tool in the management toolbox.

 

Much has changed since boxwood blight was first discovered in the U.S. in 2011.  At the time, it was widely believed the disease spelled the end of boxwoods in our landscapes.  However, research studies conducted since that time by universities and others are proving this to be a premature prognosis.

 

Both the VT and UK fact sheets, as well as other university-based resources, provide workable boxwood blight management plans for nurseries and for landscapes where the total removal of boxwoods is not a viable option.  They involve confirming boxwood blight through sending samples to plant and pest diagnostic labs, removing and destroying infected boxwoods, replanting using less susceptible types, and making fungicidal applications to protect non-infected plants.

 

Funding Research to Keep Boxwoods in Our Future

It is important to note that research continues on boxwood blight susceptibility as well as fungicide efficacy.  The bottom line is that we should not give up on boxwoods.

 

You can find out more about past and future boxwood blight research initiatives funded by the AmericanHort Foundation, Horticulture Research Institute by clicking on this hotlink:

https://www.hriresearch.org/Boxwood

 

You can support this research aimed at thwarting boxwood blight by making a charitable contribution in support of the Boxwood Fund.  Please contact the AmericanHort Foundation, Horticulture Research Institute (HRI) at 614-487-1117.  Make checks payable to HRI at 2130 Stella Ct; Columbus, OH 43215 and include a memo line: Boxwood Blight.

 

 

 

Intriguing Little Barklice

Authors Carri Jagger

Published on July 24, 2019

 

 

This week I received two emails from clients about clusters of little insects all over their trees.  After closely examining the pictures and sharing them with my Horticulture co-workers they confirmed that they were in fact Barklice.

 

Barklice are small fairly inconspicuous insects that hang out on trees eating mold, pollen, fragments of dead insects, algae and lichens.  Because of this they are actually considered be beneficial.  They do cause any harm to trees as they don’t eat bark or bore into trees.

 

These insects resemble aphids and are called lice but they are not pests or parasites of either plants or animals.  There are two species, one is Cerastipsocus venosus which is found on the bark of trees and moves as a group that resembles a herd of animals. The Cerastipsocus venosus species adult has shiny black wings which are held in tent-like fashion over their abdomens. The nymphs appear dark grey and pale yellow banding between abdominal segments. The adults and nymphs have round heads and conspicuous antennae.

 

The other species is Archipsocus nomas and they make conspicuous silken webs on the bark of tree trunks and limbs.  They are very small (less than 1/8 inch long) and soft bodied insect.  They live together under the protective layers of the silken webbing.

There is no need to control Barklice as they are harmless to plants and people.

 

More Information

https://hgic.clemson.edu/factsheet/barklice/

https://aggie-horticulture.tamu.edu/galveston/beneficials/beneficial-41_barklic…

 

 

 

The Problem with Monarchical Rule

Authors Joe Boggs

Published on July 20, 2019

 

 

This is the time of the year when the menagerie of insects that feed on members of the dogbane family (Apocynaceae), including common milkweed (Asclepias syriaca), seem to arrive en masse to the consternation of monarchists.  Some well-meaning gardeners aim to reserve milkweeds exclusively for the pleasure of monarchs.  What about other native insects that feed on milkweeds; let them eat cake?

 

Monarch butterflies (Danaus plexippus) are beautiful insects and their plight remains uncertain.  Elevated multi-national concerns over their future have raised awareness of the rewards of gardening beyond aesthetics.  Monarchs have served as excellent ambassadors for the environmental benefits of expanding our plant selection palettes to paint more diverse landscapes.  Milkweeds are no longer weeds.

 

However, efforts to save monarchs may sometimes morph into crusades to serve the aristocracy at the expense of the proletariat.  Good intentions can be taken too far.  Royal sovereignty should not rule the distribution of host plant food!

 

The Milkweed Banquet

Members of the dogbane family try to ward off herbivores by loading their milky, sticky sap with alkaloid toxins, called cardiac glycosides (cardenolides).  However, some specialized herbivores, including monarchs, evolved a capacity to handle these toxins.  The downside is that these herbivores are so specialized milkweeds are the only food they eat.  This includes a diverse range of native insects beyond monarchs.

 

Part of their dependency on milkweeds involves mounting a successful defense against predators.  Like monarch caterpillars, many of these native insects accumulate alkaloid toxins in their flesh that are acquired from feeding on milkweeds.  Presumably, this makes them taste bad, but I’ve never tested this theory.

 

Most members of the milkweed menagerie advertise their toxic character through bright coloration, usually involving an orange-on-black motif.  Employing splashy colors and color patterns to defend against being eaten is called “aposematism” from the Greek for “away” and “sign.”  Of course, as illustrated by monarchs, gaudy aposematic coloration can be beautiful.

 

Liberty, Equality, Fraternity

Notable native insects that depend on milkweeds for their livelihood include beautifully colored Milkweed Tussock Moth caterpillars (Euchaetes egle); Swamp Milkweed Leaf Beetles (Labidomera clivicollis); Red Milkweed Beetles (Tetraopes tetrophthalmus); Large Milkweed Bugs (Oncopeltus fasciatus); and Small Milkweed Bugs (Lygaeus kalmii).  These native insects have the same inalienable food rights as monarchs.

 

The small, yellow-green first instar milkweed tussock moth caterpillars have black head capsules and are covered in wispy white hairs.  Later instars sport rows of black and orange hairs punctuated by tufts of long white and black hairs; these colorful hairs are the feature most often associated with these caterpillars and are responsible for the alternate common name of “milkweed tiger moth.”

 

All instars feed side-by-side in groups sometimes called “colonies” and can consume entire leaves leaving only the veins.  In fact, the caterpillars can appear to be serious competitors to monarchs.  However, tussock moth caterpillars tend to be found on only a few milkweed plants and they focus their attention on one leaf at a time.  Plenty of food remains for monarchs.

 

The milkweed bugs are seed feeders.  They use their piercing-sucking mouthparts to skewer seeds, inject enzymes to dissolve the internal tissue, and suck-up the resulting slurry.  The bugs may also feed on developing seed pods but seldom cause enough damage to kill the entire pod.  They will reduce the number of viable seeds; however, milkweeds are prolific seed producers.  How many seeds are enough to carry milkweeds to next season?  There’s plenty of seed to go around.

 

However, I recently observed what happens when large milkweed bugs arrive before their seed-food matures:  they become cannibals.  They use their digestive enzymes on one another to suck-up the essence of insect.  It’s a jungle out there.

 

Brightly colored swamp milkweed leaf beetles (Labidomera clivicollis, family Chrysomelidae) are one of my favorites; partly because they are somewhat rare.  Despite their common name, both the adults and larvae feed on the leaves of several members of the dogbane family.

 

Although swamp milkweed leaf beetles use milkweed toxins as a chemical defense, there can be too much of a good thing.  The latex in the sticky sap can clog their chewing mouthparts.  To avoid this, both the adults and larvae will chew through veins “upstream” from their feeding site to reduce sap flow.  Evidence of beetle damage includes deep leaf notching usually towards the leaf tip.

 

The tubular-shaped red milkweed beetles are a type of longhorned beetle (family Cerambycidae).  Although the “longhorned” name of the family refers to long antennae, milkweed beetles have relatively short antennae.  However, a close examination of their prominent black antennae will reveal another family trait.  Their antennae bisect their compound eyes creating two sets of eyes with one set located above the antennae and one set below.  The name of the genus, Tetraopes, and specific epithet, tetrophthalmus, describes this unusual feature; both are derived from the Latin for “four eyes.”

 

Red milkweed beetles feed on entire plants with the adults feeding on the leaves and the larvae boring into the roots and stems.  However, I’ve never seen enough damage to present a serious challenge to monarchs.

 

I support monarch recovery.  However, we should embrace all native insects with equal affection.  I mean this figuratively since tussock moth caterpillars have defensive hairs and milkweed bugs can drill fingers with their piercing-sucking mouthparts.  Members of our native milkweed menagerie should enjoy the same natural born rights to milkweeds as monarchs.  The bottom line:  liberty, equality, and fraternity for all insects that you may find sharing milkweeds with monarchs.

 

 

 

Is it a Sawfly Larva or a Caterpillar?

Authors Joe Boggs

Published on July 18, 2019

 

 

Whenever I hear that the naturally occurring biological insecticide Bacillus thuringiensis var. kurstaki (Btk) is not killing caterpillars, the first thing I try to find out is whether or not the “caterpillars” are actually caterpillars.  Btk products (e.g. Dipel, Thuricide, etc.) only kill caterpillars, they do not kill sawfly larvae.

 

Caterpillars belong to the order Lepidoptera meaning they grow up to become butterflies or moths.  Many types of sawfly larvae look like caterpillars and even feed like caterpillars, but they are related to bees, wasps, and ants; they belong to the order Hymenoptera.  On the other hand, there are some caterpillars like Zebra Caterpillars (Melanchra picta) that look like sawfly larvae.

 

There’s an easy way to tell the difference between caterpillars and sawfly larvae using a system taught to me by Dave Shetlar (OSU Entomology, Professor Emeritus).  Although others may have happened upon this handy system, I always refer to it as the “Shetlar Method.”

 

A Little Anatomy

Starting from the head and working towards the backend, the first group of legs you find on both caterpillars and sawfly larvae are three pairs of thoracic legs.  These match with the three pairs of legs found on the adults.  The next multiple pairs of fleshy legs are called abdominal prolegs and the last pair of fleshy legs located at the backend are appropriately called anal prolegs.

 

Adult insects use their legs for locomotion, or for just standing around thinking insect thoughts if insects think.  Caterpillar and sawfly larvae primarily use their thoracic legs for holding onto things; they crawl around using their prolegs.

 

Count the Prolegs

Count the number of abdominal prolegs; do not count the anal prolegs.  Caterpillars have 5 or fewer pairs of abdominal prolegs.  Sawfly larvae have 6 or more pairs of abdominal prolegs.

 

Here’s a handy way to remember this:  Caterpillars have the same number or fewer pairs of abdominal prolegs as the fingers on your hand; sawfly larvae have more pairs of abdominal prolegs than the fingers on your hand.

 

 

 

Be Alert for Dogwood Sawfly

Authors Joe Boggs

Published on July 18, 2019

 

 

The common name of “Dogwood Sawfly” was officially assigned years ago when it was believed there was only one species, Macremphytus tarsatus.  However, taxonomists later found there are actually three species of sawflies in the genus Macremphytus that feed on dogwood leaves in the eastern U.S. including Ohio:  M. testaceusM. semicornis; and M. tarsatus.

 

Regardless, the three species share a number of characteristics:  they have one generation per season; they are mid-season pests; they may be found feeding on several species of dogwood, and their final instar larvae often bore into wood to spend the winter.  They also change their appearance as they molt from one instar stage to the next.

 

However, dogwood sawfly (M. testaceus) larvae are the true chameleons.  Newly hatched larvae look like small caterpillars; they are amber in color and are somewhat transparent.  The larvae emerge from their second molt covered with a white powdery material.

 

When the larvae are resting, they curl into a knot and look like bird droppings to the casual observer.  At their final molt, the larvae are about 1″ in length and they lose their white powdery covering, revealing a yellow body with black patches.  This final color phase is shared with the other two species.

 

The behavior and damage caused by the larvae of this and the other two sawfly species also change as they develop.  The newly hatched larvae feed together, skeletonizing the leaves.  As the larvae mature, they consume the entire leaf, except the mid-vein.  Individual branches or entire plants may be completely defoliated.  I’m always amazed at how the snowy-white larvae can remain hidden until they’ve stripped all of the leaves from small dogwoods.

 

The mature yellow and black larvae crawl from their host trees in search of overwintering sites; they may be found crawling along fence rails, sidewalks, etc.  Aside from sometimes appearing in unexpected places which may produce a misidentification, the mature sawfly larvae also practice an unusual overwintering behavior which can misdirect identification.

 

The mature larvae may bore into softwood, if available, to produce an overwintering chamber.  While they usually select decaying wood, the larvae may occasionally bore into redwood siding or outdoor furniture.  Thus, they are sometimes mistaken for a true wood-boring insect.

 

Management

Dogwood sawfly damage is well underway for this season.  However, further defoliation can be halted by knocking the larvae onto the ground to stomp them or into a bucket of soapy water to drown them.  Insecticides may also be used including biorationals such as azadirachtin and spinosad or conventional insecticides such as pyrethroids (e.g. bifenthrin, permethrin, etc.).

 

The naturally occurring biological insecticide Bacillus thuringiensis var. kurstaki (Btk) (e.g. Dipel, Thuricide, etc.) does not kill sawfly larvae; it only kills caterpillars.  To be able to tell the difference, read my next BYGL Alert.

 

 

 

Gypsy Moth Adults Take Flight

Authors Amy Stone

Published on July 18, 2019

 

 

The caterpillar feeding frenzy has ended for the year and adult activity is being observed in NW Ohio. The male moths have taken flight in their zig-zag pattern in hopes of finding a mate. The female moths are white and a bit larger in size, and typically don’t move far distances from the pupal casing that they emerged from. She gives off a pheromone to alert close by males of her location. After a visit from the male moth, she will begin laying eggs. The mass of eggs laid now, will remain in that stage until the following spring, as there is one generation per year.

 

It is the same pheromone “fragrance” used in the lure, placed in the traps set and monitored across the buckeye state by the Ohio Department of Agriculture (ODA) (see photo below). The data collected from those traps will help as a guide for the state program, that is part of a larger national program coordinated by the USDA Forest Service. Traps monitor the progression, or maybe even regression, of the leading edge and also alert regulators to “hot-spots” that could be building in a particular area.

 

Adult activity, and more importantly number and size of the egg masses, are tools to help determine what is on the horizon and can aid in predictions of how populations number look for the 2020 season.

 

For additional information about the gypsy moth and state coordinated suppression treatments, check out the ODA website at: https://agri.ohio.gov/wps/portal/gov/oda/divisions/plant-health/gypsy-moth-program/gypsy-moth-program

 

 

 

Perspectives on Sudden Oak Death (SOD)

Authors Jim Chatfield  Joe Boggs

Published on July 17, 2019

Reviewed and Additions Provided by:

Dr. Pierluigi (Enrico) Bonello

Dr. Francesca Peduto Hand

The Ohio State University, Department of Plant Pathology

 

 

The Ohio Department of Agriculture (ODA) has announced in an official press release a confirmed interception of the plant disease-causing pathogen Phytophthora ramorum in Ohio.  You can access the press release by clicking on the hotlink at the end of this Alert.

 

  1. ramorumis a water mold organism that causes ramorum blight on over 100 host plants, including rhododendron and lilac, and sudden oak death (SOD) in coastal areas of California and Oregon.  SOD has proven to be deadly in California and the Pacific Northwest on oaks (Quercus) and tanoaks (Notholithocarpus). On other hosts, this pathogen causes leaf spots and branch dieback.

 

A shipment of infected plants, including numerous rhododendron types and lilac, from a nursery in the Pacific Northwest, was sent to a nursery in Oklahoma and subsequently shipped to Walmart and Rural King locations in a number of eastern U.S. states, including Ohio. Though this pathogen was found on rhododendrons and lilacs intercepted here, there was no shipment of oaks with SOD.

 

For context, it is important to remember the Plant Disease Triangle:  a susceptible host, a virulent pathogen, and an environment conducive to disease are all necessary for a particular disease to occur. Over the almost 25 years in which SOD and ramorum blight have been regulated disease issues, we do not know of any cases of this disease becoming established in the U.S. other than those coastal areas of California and the Pacific Northwest.

 

Although it is impossible to completely know for certain the potential risk of this pathogen becoming established here, Ohio is not considered to be a particularly likely candidate for establishment of SOD.  P. ramorum has never been detected before in Ohio nurseries, landscapes, or forests. That said, the vigilance of ODA and our plant regulatory system should be lauded relative to this interception.

 

Let us proceed with caution. If your customers have rhododendrons or lilacs purchased at Walmart or Rural King between March and May of this year and you suspect they may be infected, drawing from the ODA Press Release, “Plants can be destroyed by burning, deep burial or double-bagging the plant, including the root ball, in heavy duty trash bags for disposal into a sanitary landfill (where allowable).  Consumers should not compost or dispose of the plant material in municipal yard waste.”

 

In addition, it is important to keep in mind there are many different diseases, insects, and physiological problems that may occur on rhododendrons, lilacs, and oak.  To sharpen your plant problem diagnostic skills, we will make a point of reviewing some of these at diagnostic training events yet to come this summer and fall.  These include a workshop that will be held on the OSU-Mansfield Campus on August 2 and the Ohio Plant Diagnostic Workshop on the OSU-Wooster Campus on September 6 as well as the Greater Cincinnati Diagnostic Walk-Abouts on August 5, September 9, and October 14.

 

You can access the ODA Press Release by clicking this hotlink:

https://agri.ohio.gov/wps/portal/gov/oda/divisions/plant-health/invasive-pests/p-ramorum-survey

 

 

 

Walnut Petiole Gall

Authors Joe Boggs

Published on July 17, 2019

 

 

While taking pictures of Walnut Caterpillars (Datana ministra), I noticed that the sometimes caterpillar-like Walnut Petiole Galls produced by the eriophyid mite, Aceria caulis (family Eriophyidae), are reaching their maximum size and becoming very evident on their namesake host.  The galls are specific to black walnut (Juglans nigra) and may occur on the petiole, rachis, and petiolules of the compound leaf.

 

The galls are covered in densely compacted hairs that resemble the erineum patches produced by other eriophyid mites.  As the galls “mature,” they change color from pinkish-white to pink to deep red and finally to dark brown.  They may be very obvious causing tree owners to fear for the health of their trees

 

Although the galls may cause the compound leaves to become twisted and malformed, they do not disrupt the vascular flow.  The affected food-producing leaflets remain functional even though they may be pointed in an array of directions.  Thus, the eriophyid galls do not appear to cause significant harm to the overall health of their walnut hosts.

 

There are online recommendations to remove and destroy the galls on small trees to reduce the mite population.  However, this could mean removing a considerable number of food-contributing leaves making the treatment more damaging than the condition.  Besides, as with many plant gall-makers, populations of this eriophyid appear to rise and fall dramatically from year-to-year.  I seldom see heavy galling two years in a row on the same walnut tree.

 

 

 

Plant of the Week – Purple Beautyberry

Authors Amy Stone

Published on July 17, 2019

 

 

The small pinkish flowers caught my eye the other day as I was walking through the garden. While not overly showy, and maybe not even noticed by many, the fruit to follow with be breath taking. The flowers remind of the “beauty” of the berries, just around the corner.

 

Purple beautyberry (Callicarpa dichotoma), is described by Michael Dirr as the most graceful and refined of the species.  Some cultivars include: ‘Early Amethyst’, ‘Issai’, and ‘Duet’.

 

The oppositely arranged leaves act as a staging area for the purple fruits to come. The berries line the arching stems and are interesting, beginning late summer through fall.

 

Purple beautyberry can be planted in full sun to part-shade. I have observed it planted in masses, in a mixed garden, and as a hedge row – with my favorite being a serpentine hedge as the summer and fall “bones” of a perennial garden. It can be a little late to get going in the spring. In fact, we can see some branch dieback after a cold winter when temperatures bottom out. If this is the case, cutting the shrub down to the base is recommended and new growth will begin.

 

More Information

Missouri Botanical Garden, Plant Finder

http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kemp…

 

 

 

Walnut Cats on the Prowl

Authors Joe Boggs

Published on July 17, 2019

 

 

First-generation Walnut Caterpillars (Datana ministra) are producing noticeable defoliation in southwest Ohio.  The moth caterpillars feed in groups, or “colonies,” of 10-30 individuals throughout their development which is why their defoliation is often focused on a single branch or a group of adjoining branches.

 

As their common name implies, walnut caterpillars are most often found on walnut trees, but they will also feed on hickory and pecan trees and will occasionally infest apple, birch, honeylocust, oak, and willow.  Large established trees can typically handle the defoliation with little long-term impact on overall tree health; even when infested by multiple colonies.  However, multiple colonies on small trees can cause significant harm.

 

Walnut caterpillars practice an interesting defense behavior.  When disturbed, the caterpillars will rear their front and tail ends, often in unison, presumably to confuse predators.  Thus, these caterpillars have great entertainment value!

 

They also practice an unusual molting behavior.  When molting, they group together on trunks, branches, or twigs and all of the caterpillars molt at the same time leaving behind a mass of hairy exoskeletons that looks like a patch of fur.  Finding these furry patches on or near denuded walnut leaves is a good way to identify the culprit behind the defoliation.

 

It’s Just a Phase

The caterpillars pass through distinct “color phases” during their development meaning they change their colors and markings as they mature.  There is some debate about whether or not it’s 3 or 4 color phases.  Regardless, the changes in colors, markings, and furriness may present a challenge with their identification.

 

There are at least two generations per year in southern Ohio with some indications there may be only one generation in the northern part of the state.  It appears we are nearing the end of the first generation in Greater Cincinnati.

 

Management

Walnut caterpillars have a wide array of natural enemies from birds to insect predators to insect parasitoids and insect pathogens.  These natural controls can keep populations in check; however, there may be occasionally caterpillar outbreaks as is common for native insects.

 

Early instar walnut caterpillars can be effectively controlled using the naturally occurring biological insecticide Bacillus thuringiensis var. kurstaki (Btk) (e.g. Dipel, Thuricide, etc.).  Fortunately, Btk does not kill bio-allies that help provide natural control of the caterpillar populations.

 

Unfortunately, Btk is most effective on small caterpillars and becomes much less effective when caterpillars reach the middle instar stages. Btk is a stomach poison which means it must be consumed to kill the caterpillars and it has relatively short residual activity.  Thus, two applications may be required.

 

The large caterpillars can be easily managed on small landscape trees using a two-step control method.  Step one involves knocking the caterpillars to the ground.  Step two consists of performing the “caterpillar stomp.”  Thus far, no walnut caterpillars have become resistant to this control method.

 

 

 

Buzz-Bombing Beetles are on the Wing

Authors Joe Boggs

Published on July 16, 2019

 

 

Green June Beetles (Cotinis nitida, family Scarabaeidae) are practicing their annual terrorizing of backyard gardeners, golfers, sunbathers, small pets, etc., as they buzz golf courses and lawns.  Despite the “June” in their common name, these beetles appear on the scene in July in Ohio.

 

The large, metallic green beetles tend to emerge en masse.  Their large size, coupled with an audible “buzzing” sound and low-level flight plan; cruising at about 2 – 3′ above the ground, may induce mild panic in the uninitiated.  In fact, as I discovered in my (misspent) youth, the attractive beetles have great entertainment value.  Tying a string to a hind leg of one of these powerful flyers turned the beetle into a drone before there were drones.

 

Adults feed on tree leaves as skeletonizers, or they may be found on ripening fruit.  They rarely cause significant leaf injury; however, they may seriously damage fruits.

 

The beetles seek turfgrass with high levels of organic matter (e.g. thatch) in which to lay eggs.  It has been speculated that this attraction to decomposing organic matter explains why large numbers of adults will cruise above certain lawns while ignoring neighboring lawns.

 

Unlike other Scarab beetle larvae found in turfgrass, green June beetle grubs burrow 10 – 12″ vertically into the soil and they remain closely associated with these burrows.  The grubs exit their burrows at night to feed on thatch and other organic matter.

 

This is one of the largest and strangest white grubs you’ll ever see in Ohio.  First, the mature grubs are huge measuring well over 1″ in length.  They look like white grubs on steroids.

 

Second, the grubs practice an unusual mode of locomotion:  they crawl along on their backs in an undulating motion.  Their rolling motion causes them to superficially resemble caterpillars.  Their legs are smaller than those of other white grubs in relation to the size of their bodies.  Some have speculated their leg-size is an adaptation to life in a burrow while their unusual style of crawling reconciles having small legs.  Regardless, the upside-down grubs are surprisingly fast.

 

Despite their large size, green June beetle larvae seldom cause injury to turf equal to that caused by Japanese beetles or masked chafers. They are mostly considered a nuisance pest.  Control efforts should focus on reducing organic matter, particularly thatch, beneath infested lawns.  For example, thatch reduction using core aeration to enhance aerobic decomposition will eventually make infested lawns less attractive to these buzz-bombing beetles.

 

 

 

An American Tail: the Lotus and its Caterpillar

Authors Joe Boggs

Published on July 16, 2019

 

 

If you’re in Greater Cincinnati and have the chance visit the beautiful Glenwood Gardens [Great Parks of Hamilton County], grab a map at the main office and ask how to hike to the “Lotus Pond.”  It’s a bit of a hike, but do what I did and wait until the afternoon temperature climbs above 90 F. and the humidity allows you to wear the air.  Who needs a sauna?

 

Your intrepid perseverance may be rewarded by a display of American lotus (Nelumbo lutea). It’s one of my favorite native wildflowers and is also known as water-chinquapin and yellow lotus.  In my opinion, there is nothing else that rises from our waters to rival the allure of this aquatic beauty.

 

Fragrant yellowish-white flowers (lutea means yellow) opening up to 10″ wide.  Deep green exotic-looking leaves stretching almost 3′ in diameter.  What’s not to like?  Even the showerhead seed pods draw interest.  Of course, there are those who may not share my enthusiasm for this native aquatic plant, but more about that later.

 

There are only two species of lotus worldwide:  the American lotus and the sacred lotus (N. nucifera) which is also called the Indian, Asian, or pink lotus.  Both lotus species once belonged to the water-lily family, Nymphaeaceae, in the plant order Nymphaeales.

 

However, based on DNA sequencing, the lotuses are now placed in their own family, Nelumbonaceae, and moved to a different order, Proteales.  This order also includes the plane family, Platanaceae.  This means American lotus is more closely related to American sycamore (Platanus occidentalis) than it is to any of the water-lilies.

 

The apparent similarities between lotus and water-lilies are now considered the result of convergent evolution where natural selection produces comparable features among unrelated or distantly related organisms.  A frequently used example are bats, birds, and insects all having wings.

 

American lotus colonies spread by seeds and submerged rhizomes.  The plants are not free-floating; they are firmly rooted in submerged soil.  That’s why plants grow around the edges of ponds or in the shallow waters of lake inlets or river backwaters; oxbows are a favored location.

 

The large lotus leaves are coated in epicuticular waxes.  I’ve always appreciated how droplets of rainwater that collect in the leaf centers glisten gem-like in the sun.  The leaves and stems have milky sap which has a number of interesting attributes including alkaloids that have been shown to have anti-bacterial properties.

 

The lotus plants provide a healthy habitat for a wide range of micro and macro-organisms.  The large leaves protect immature fish from predators, the seeds are utilized by ducks and other migratory birds, and the rhizomes are eaten by beavers and muskrats.

 

American lotus can be enjoyed in a number of locations around Ohio beyond Glenwood Gardens.  You can find it growing in shallow inlets along Lake Erie as well as Tappan Lake in northeast Ohio and in the shallow upper reaches of Cowan Lake located just southwest of Wilmington, OH.  Indeed, there was once a trail in Cowan Lake State Park called “Lotus Cove.”  However, while lotus continues to grow in the lake, the cove is choked with silt and the trail is now defunct.

 

Not everyone views American lotus with the same appreciation.  Although native, it can be aggressive in colonizing shallow waters creating a challenge to those who pursue other aquatic beauties such as bass, sunfish, etc., and aquatic activities like boating and water skiing.

 

Some Lotus May Be Sacred

Don’t confuse American lotus with its non-native cousin; the sacred lotus.  Unfortunately, this lotus has found its way into some Ohio waters which is why it is included in the Ohio Field Guide to Aquatic Invasive Species.

 

The color of the flowers provides a helpful way to tell the difference between our native lotus and the non-native sacred lotus.  American lotus flowers are yellow to yellowish-cream colored.  Although there are a few varieties and cultivars of sacred lotus that also produce light yellow flowers, most produce flowers that are pink or tinged with pink which is why it’s sometimes simply called the pink lotus.

 

You can learn more about identifying invasive aquatics in Ohio including the sacred lotus by clicking on this hotlink:

http://ohiodnr.gov/Portals/wildlife/pdfs/species%20and%20habitats/OSU_AIS_FieldGuide_Web.pdf

 

The Caterpillar

The American Lotus Borer (Ostrinia penitalis (Lepidoptera: Crambidae)) can be a significant pest of American and sacred lotus in Ohio.  The most obvious symptom is the skeletonizing-like leaf damage that’s currently giving a ragged appearance to lotus leaves in Cowan Lake and in the Glenwood Gardens Lotus Pond.

 

The caterpillar is found throughout North America as well as the Amazon basin of South America; the same range as its American lotus host.  The moth has two generations per season in Ohio.  The current leaf damage is being caused by the first generation; damage by the second generation is typically more severe.  Despite its common name, the borer has also been found feeding on various smartweeds (Polygonum spp.).

 

On lotus, early instar caterpillars are found on the upper leaf where they use silk to pull together two radiating leaf veins creating a shallow trough-like depression.  Individual caterpillars reside within these depressions covered by a dense mat of silk which presumably prevents them from falling into the water and provides camouflage against predators.  The ruse is not always effective as there are reports of redwing blackbirds shredding leaves in search of the caterpillars.

 

The caterpillars feed beneath their webbed abodes and also venture forth, apparently mostly at night, to feed on the surrounding leaf surface.  During this time, the caterpillars remain anchored to the leaf with silk; an adaptation to their aquatic environment preventing them from being washed away by waves.

 

True to their common name, as the larvae mature, they eventually change their feeding habits to become borers.  The caterpillars burrow into the leaf petiole where the petiole attaches to the leaf and feed by tunneling down the petiole.  Their stem boring activity isn’t just confined to the leaf petioles.  The caterpillars also tunnel the flower stems to eventually find their way into the seed heads.  In fact, this is where the second generation larvae pupate to spend the winter.

 

There are records of the borer causing serious damage to all parts of its native and non-native lotus hosts including significantly reducing seed production.  Indeed, I observed severe leaf damage to the lotus in Cowan Lake.  Other than physically removing the caterpillars from the leaves and stems, there are no other effective controls.

 

Fortunately, as with any native insect, populations tend to rise and fall dramatically from year to year, so the borer seldom causes significant long-term damage to a colony of American lotus.  It appears that established American lotus colonies have the ability to recover from the periodical onslaught by its caterpillar.

 

 

 

 

OHIO STATE UNIVERSITY EXTENSION

 

Where trade names are used, no discrimination is intended and no endorsement by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.

Ohio State University Extension embraces human diversity and is committed to ensuring that all research and related educational programs are available to clientele on a nondiscriminatory basis without regard to race, color, religion, sex, age, national origin, sexual orientation, gender identity or expression, disability, or veteran status. This statement is in accordance with United States Civil Rights Laws and the USDA.

CFAES provides research and related educational programs to clientele on a nondiscriminatory basis. For more information: [ http://go.osu.edu/cfaesdiversity ].

Any materials in this newsletter may be reproduced for educational purposes providing the source is credited.

 

BYGL Weekly News for July 8, 2019

BYGL Weekly News for July 8, 2019

The following articles were compiled during the last 7 days by members of the Extension, Nursery, Landscape, Turf (ENLT) team to benefit those who are managing a commercial nursery, garden center, or landscape business or someone who just wants to keep their yard looking good all summer.  Access the BYGL website for additional information on other seasonal topics at: http://bygl.osu.edu

 

Assassins are Roaming Around, but Don’t Panic

Authors Joe Boggs

Published on July 6, 2019

 

 

Insects belonging to the Hemipteran family Reduviidae are collectively known as “Assassin Bugs.”  The family includes over 190 species in North America and they are all are meat eaters.  The common name for the family clearly describes how these stealthy hunters make a living.

 

Family members sport potent predatory equipment including strong raptorial front legs for seizing and holding prey and powerful piercing-sucking mouthparts to suck the life out of their victims.  Assassins are highly effective stealthy hunters able to sneak up on some of the most powerful and well-armed insects.  I once watched an assassin bug grab and dispatch a bald-faced hornet which is no easy meal.

 

Some assassin bugs like those in the genus Zelus have additional assistance with their grabbing power in the form of a sticky goo covering their front legs.  The gluey material is produced by glands on their front legs making them function like sticky fly paper.  You may find the Pale Green Assassin Bug (Z. luridus) hanging out on flowers waiting to grab a quick meal with their sticky legs.

 

Once the assassins seize their prey, they use their piercing-sucking mouthparts, called a “beak,” to inject paralyzing and pre-digestive enzymes.  In their final insecticidal act, the assassins suck out the essence-of-insect from their hapless victim.

 

Assassin bugs pass through three developmental stages:  eggs, nymphs, and adults.  This is known as “incomplete metamorphosis.”  However, unlike other incomplete metamorphic insects such as grasshoppers with the nymphs resembling miniature adults, the nymphs of some assassin bugs may look nothing like the adults.

 

In fact, the nymphs of our native Wheel Bug (Arilus cristatus) are often mistaken for spiders.  The nymphs have long, spindly spider-like legs and they parade around with their abdomens held upright.  Of course, insects have six legs and spiders have eight legs.

 

Wheel bugs are one of the largest and most common assassin bugs found in Ohio.  Their name refers to a peculiar morphological feature that rises from the top of the adult bug’s thorax.  The structure looks like half of a cogwheel, with the gear teeth clearly visible.  Wheel bugs are big, measuring almost 1 1/2″ long, and their color varies from light gray to bluish-gray to grayish-brown.

 

Caterpillars and sawfly larvae are favored table fare of these voracious predators; however, they will not turn their beaks up at other arthropod meat morsels.  Indeed, they will even nail the probing fingers of uninformed gardeners!

 

While these are beneficial insects, they should not be handled.  All members of the family are capable of delivering a painful bite to people.  The pain of a bug bite has been described as being equal to or more powerful than a hornet sting, and the wound may take over a week to heal.  It is best to appreciate these beneficial insects from afar.

 

A Bug-Induced Panic

Wheel bugs were at the center of a bug hysteria that swept through Ohio as well as several other states in 2015.  The panic was induced through a series of unfortunate events starting with wheel bugs being misidentified as kissing bugs (Triatoma spp., family Reduviidae).

 

The name “kissing bug” may sound non-threatening until you learn why they were given that name.  Several species of bugs belonging to the genus Triatoma are collectively known as “kissing bugs” because they tend to bite near a person’s mouth.  These “triatomine bugs” get away with their cheeky behavior by biting people while they sleep.

 

The bites are usually painless but may lead to a serious disease if the bugs are harboring the protozoan Trypanosoma cruzi in their gut.  The bugs don’t inject the protozoan when they bite; they release it from their other end when they defecate.  Infection occurs if the protozoan is accidentally rubbed into the bug’s feeding wounds or onto mucous membranes such as nasal passages.  The resulting Chagas disease is nothing to sneeze at; it can be deadly.

 

Thankfully, the kissing bug / Chagas disease connection only occurs in Central and South America with some rare occurrences in Texas.  Conditions don’t support the same relationship here in Ohio.

 

Even though wheel bugs and kissing bugs belong to the same family, their lifestyles are completely different.  Wheel bugs suck insect juice; kissing bugs suck animal blood.

 

However, with their long spindly legs, large bodies, narrow heads with beady eyes, wheel bugs do share family features with their kissing cousins.  Consequently, pictures of wheel bugs started showing up on the Web identified as kissing bugs.  That spawned an alarm that rippled through several media outlets.

 

The second round of bug-induced panic occurred back in April.  This time, it was based on the reality that there is a kissing bug called the Bloodsucking Conenose (Triatoma sanguisuga) that may be found in the northern U.S. including Ohio.  Although it has a scary sounding common name, the conenose is very rare in Ohio and it doesn’t acquire and spread the protozoan responsible for Chagas disease.  You can read about this second panic in a BYGL Alert that I posted on April 25 titled, “Kissing Bug Hysteria Rises Again,” by clicking on this hotlink:  https://bygl.osu.edu/index.php/node/1243

 

 

 

Dog-Day Cicadas and Cicada Killers

Authors Joe Boggs

Published on July 5, 2019

 

 

Annual Dog-Day Cicadas (Tibicen spp.; family Cicadidae) are starting to sing in southern Ohio.  This means their nemesis, Cicada Killer Wasps (Sphecius speciosus), will soon be seen cruising woodlands and landscapes in search of their exclusive prey.

 

The annual cicadas share several behavioral traits with periodical cicadas (Magicicada spp.; family Cicadidae).  The nymphs of both types of cicadas develop underground sustained by juices sucked from tree roots and it takes multiple years for them to complete their development from eggs to new adults.

 

Periodical cicadas are so-named because it takes 17 or 13 years for new adults to emerge en masse in spring.  It takes 2-3 years for dog-day cicada nymphs to complete their development; however, some adults emerge every year due to overlapping generations.  The adults appear sporadically throughout the “dog days” of summer usually beginning in July.

 

Like their periodical familial cousins, dog-day cicada males also “sing” to attract females.  However, they do not “chorus” with large numbers synchronizing their song.  An occasional dog-day cicada buzzing to entice a female doesn’t compare to the cacophony created by a multitude of periodical cicadas.  It’s like comparing a barbershop quartet to a million man chorus!

 

As with periodical cicadas, dog-day cicada females use their long, spade-like ovipositors to insert eggs through the bark of twigs and into the white wood.  The resulting damage splits the bark and white wood leaving deep longitudinal furrows of ruptured tissue.  The injury often causes the twig to die, the leaves to turn brown (“flag”), and the twig to detach and drop.   However, owing to the smaller numbers of dog-day cicadas, their egg-laying damage usually goes unnoticed.

 

Dog-Day Cicada Nemesis

Cicada killer wasps feed exclusively on annual dog-day cicadas; they do not prey upon periodical cicadas.  That’s why the wasps appear on the scene long after a periodical cicada brood emergence has left the scene.  The synchrony with annual cicadas makes sense if you consider that the wasps would starve to death waiting 13 or 17 years for a cicada meal.

 

The wasps measure 1 1/8 to 1 5/8″ in length and are one of the largest wasps found in Ohio.   As with all Hymenoptera (wasps, bees, etc.), only the females possess stingers (ovipositors); however, they are not aggressive.  The males are aggressive, but they lack stingers.

 

The females spend their time digging and provisioning burrows with paralyzed cicada-prey.  They prefer to dig their brood burrows in bare, well-drained soil that is exposed to full sunlight.  Although the wasps are considered solitary, all of the females have the same nesting requirements.  So it is not unusual for there to be numerous burrows, and wasps, in relatively small areas.

 

The males spend their time establishing and defending territories that encompass multiple females.  They are notoriously defensive and will aggressively buzz any transgressor who dares to enter their territory including other males as well as picnickers, golfers, volleyball enthusiasts, and gardeners.  Fortunately, it’s all a rouse since they lack the necessary equipment to deliver a sting.

 

Cicada killers are considered beneficial insects.  However, their large size coupled with low-level flights over sand volleyball courts, sparse lawns, and bare areas in landscapes can be disconcerting generating demands for control options.

 

Insecticide applications to kill the killers is not recommended.  First, they are beneficial insects.  Second, the females are not aggressive; stinging encounters are very rare.  Finally, the best way to manage cicada killers is to modify their habitat.  Renovating lawns late this summer to thicken the turfgrass will keep the killers out of lawns.  Applying mulch to cover bare soil or raking mulch to disturb and redistribute possible burrowing sites will convince females to nest elsewhere.  The same is true for golf course sand traps and sand volleyball courts:  periodical raking will prevent the wasps from becoming established.

 

A Word about Big Wasps

The annual appearance of our native cicada killer wasps invariably triggers e-mails and phone calls to Extensioneers in Ohio and elsewhere about Asian Giant Hornets (Vespa mandarinia) or the subspecies, Japanese Giant Hornets (V. m. japonica).  To be clear:  these non-native hornets have never been confirmed in Ohio or elsewhere in North America.

 

Unfortunately, some online postings of Asian hornets “found” in the U.S. show images of European Hornets (V. crabro), which are rare but can be found in the U.S. including Ohio, or cicada killer wasps.  This is not to say the Asian giants won’t appear in the U.S., but please get a confirmation from an official agency (e.g. ODA, USDA APHIS, etc.) before adding to the web confusion.

 

 

 

Planthoppers Abound

Authors Joe Boggs

Published on July 5, 2019

 

 

Flatid planthoppers (family Flatidae, order Hemiptera) are relatively small insects with the adults measuring no more than around 1/4″ in length.  The adults and immatures (nymphs) look nothing alike which can lead to identification issues with connecting one to the other.

 

The adults of many species have broadly triangular shaped front wings that they hold tent-like over their abdomens.  The adults are commonly found resting on plant stems and are often mistaken for moths.

 

A good example is provided by the Citrus Flatid Planthopper (Metcalfa pruinosa).  Despite its common name, this planthopper is commonly found in Ohio.  It ranges throughout the eastern U.S. from Maine to Florida where true to its common name, it’s often found on citrus.

 

Early instar nymphs are often obscured by a dense cloak of tangled waxy, white, cotton-like “fluff.”  They congregate in groups, or “colonies,” and their profusion of flocculent material on plant stems may cause them to be mistaken for woolly aphids or mealybugs.  Late instar nymphs look like some form of Star Wars troop vehicle with tufts of white filaments streaming behind.

 

Clusters planthopper nymphs are appearing on plants in southwest Ohio.  They are most commonly found in woodlands, but will occasionally creep up the stems of plants in landscapes as well as vegetable gardens.  They are most often found near the ground; however, I was surprised to find fluffy clusters at around eye-level on the stems and leaves of several woody ornamentals.

 

Like their aphid, mealybug, and soft-scale cousins, flatid planthopper adults and nymphs use their piercing-sucking mouthparts into phloem vessels to tap plant sap.  They discharge the excess sugar-rich liquid from their anus in the form of a sticky, sugar fluid called “honeydew” which can become colonized by black sooty molds.

 

Fortunately, flatid planthoppers seldom rise above the status of nuisance pests.  However, their resemblance to other sucking insects that cloak themselves in white, cotton-like material can lead to misidentifications.

 

Nymphs can be washed from plant stems using a coarse stream of water from a garden hose which will also wash away the white “fluff.”  Insecticide applications are seldom warranted, but if needed, insecticidal soap applications are highly effective and will preserve the hopper’s natural enemies.

 

 

 

Turfgrass Times, 06.28.2019

Authors Amy Stone

Published on July 2, 2019

 

 

Here is your link to the weekly video update (recorded on 06.28.2019) from the OSU Turfgrass Team. Updates are from Dr. David Shetlar, aka The Bug Doc; Dr. David Gardner; Dr. Ed Nangle; Dr. Pamela Sherratt (virtual); Joe Rimelspach; and Michael O’Keeffe this week.

 

https://vimeo.com/345052184

 

 

 

Sumac Gall Aphid: An International Story

Authors Joe Boggs

Published on July 2, 2019

 

 

The bladder-like galls produced the Sumac Gall Aphid (Melaphis rhois) are becoming evident on the leaflet midveins of its namesake host in southwest Ohio.  They currently measure between around 1/4″ to 1/2″ in diameter and their size coupled with their light green color can make them difficult to detect.

 

This will change as the season progresses.  The galls will eventually become variegated with areas that are greenish-white bounded by areas that are mottled reddish-pink.  The starkly contrasting colors will make the galls very evident.

 

The online literature indicates smooth sumac (Rhus glabra) and staghorn sumac (R. typhina) are the aphid’s primary hosts, if not the only sumac hosts.  I’ve never found them on any other sumac.

 

As with the vast majority of insects that produce plant galls, the sumac gall aphid appears to cause little injury to the overall health of their host plants.  Although heavy galling may cause early coloring and shedding of some sumac leaflets, the overall impact appears to be inconsequential relative to plant health.

 

The aphid has a complex life cycle with summer generations producing galls on sumac and winter generations living on mosses beneath or near the sumac.  Females released from the summer galls drop onto moss where they reproduce asexually and the subsequent generations survive the winter.

 

Males and females arise from the moss colonies in the spring with winged, mated females flying to sumac where each female lays a single egg.  The egg hatches into a “stem mother” which initiates gall formation and gives rise to a series of parthenogenetic (without males) generations that proliferate inside the gall.  The galls eventually split open in the fall to release winged females that drop onto moss starting the alternating moss-sumac host cycle over again.

 

A Deep Time International Story

In 2015, Zhumei Ren (School of Life Science, Shanxi University, Taiyuan, China) visited Greater Cincinnati on a collection trip hosted by Sue Lutz (Botanist, Smithsonian National Museum of Natural History) and funded by the Museum’s Global Genome Initiative.  Ren was doing research on prehistoric connections between gall-making aphids on sumac that are found in Asia and North America.

 

Research had clearly shown that our native sumac gall aphid, Melaphis rhois, and the Chinese sumac aphid, Schlechtendalia chinensis, are “biogeographically disjunct” Asian and North American species meaning they are related, but separated geographically.  Indeed, Ren’s research showed our native aphid’s mitochondrial genome (mitogenome) is identical to that of the Chinese aphid which begs the question:  just how “native” is our native sumac gall aphid?

 

Based on aphids Ren gathered in Ohio and elsewhere in 2015, a phylogenetic study she published in 2017 showed the North American gall aphid genus, Melaphis, diverged from its Asian relatives around 64.6 million years ago during the early Paleogene Period in the Paleocene Epoch

 

Alert readers will recognize that the timing is very close to the mass extinction that marked the end of the Cretaceous period as well as the non-avian dinosaurs (the so-called K-T Boundary).  While the exact chain of events causing the demise of T-Rex remains hotly debated, there is no doubt a meteor impact played a key role.

 

The meteor muddled-up more than just reptiles.  Owing to continental drift, Earth’s land masses were aligned differently 65 million years ago.  North America was strongly attached to Asia by more than just a land bridge across the Bering Sea.  There is no doubt many insect-plant relationships were shared between the two continents.  However, the mass extinction radically changed things [see “2002: Impact …” in “More Information” below].

 

The meteor impact appears to have scrambled the phylogenetic record in such way that science may not be able to untangle the exact historical relationship between our sumac gall aphids and those found in Asia.  At least, that’s a conclusion Ren and her co-authors presented in their 2017 paper.  Of course, if Ren’s research thus far teaches us anything, it’s that science does not stand still.  And, the lessons taught by the sumac aphid is more than just gall deep; they are deep time deep.

 

More Information

2002: Impact of the terminal Cretaceous event on plant–insect associations

http://www.pnas.org/content/99/4/2061

 

 

 

 Ailanthus Webworm: Hope Springs Eternal

Authors Joe Boggs

Published on July 1, 2019

 

 

Ailanthus Webworm (Atteva aurea) caterpillars feed exclusively on the non-native, highly invasive, misleadingly named Tree-of-Heaven (Ailanthus altissima, family Simaroubaceae).  The webworms are the larval (caterpillar) stage of a beautiful ermine moth (Family Yponomeutidae).  In my opinion, this is one of the most beautiful moths found in Ohio.

 

Multiple overlapping generations occur each season so it is common to find both moths and caterpillars active at the same time.  Both are active throughout the season with the moths appearing on both early and late-blooming plants.

 

The webworms produce communal nests by pulling leaflets into a network of loose webbing.  Several caterpillars live within the nests consuming the leaflets enveloped in their webbing.

 

The webworms can grow up to 1 – 1 1/2″ long and they have a wide, light greenish‑brown stripe down their backs and several thin, alternating white and olive green stripes along their sides.  The caterpillars are sparsely covered with short, erect hairs, which help to suspend them within the webbing.  When disturbed, the caterpillars move backward out of the nest and drop towards the ground on strands of silk.

 

Ailanthus webworms are native to tropical regions in Central and South America where the caterpillars feed on native trees in the genus Simarouba (family Simaroubaceae).  The moth was originally assigned the scientific name, Atteva punctella, and it was observed that this moth had expanded its palate to take advantage of the non-native tree-of-heaven that was flourishing in Central and South America.

 

It was once assumed the moths exploited the ever-expanding range of tree-of-heaven to move north into the U.S. and Canada.  However, research involving DNA bar-coding, moth morphology, and food plant records eventually revealed that while A. punctella and A. aurea co-inhabit tropical regions of the New World, the moth in the U.S. and Canada is, in fact, A. aurea.

 

The caterpillars are capable of defoliating their odoriferous namesake host and they may feed on stem tissue once all leaves are devoured.  Unfortunately, such extreme damage is rare on large trees.  Although feeding by this webworm has yet to halt the spread of tree-of-heaven, hope springs eternal since this is one of only a few insects known to infest this encroaching interloper.

 

 

 

A Most Beautiful Beetle

Authors Joe Boggs

Published on July 1, 2019

 

 

I post a BYGL Alert each year about Dogbane Beetles (Chrysochus auratus) because the beetle’s light-blending artistry makes it one of the most beautiful beetles found in Ohio.  Enjoying these shimmering living gems on their namesake host is the entomology equivalent to “stop and smell the roses.”

 

The beetle’s scientific name, Chrysochus auratus, loosely translates to “made of gold.”  In fact, gold is only one of a medley of colors displayed by these gorgeous native beetles.  As you change your viewing angle, the beetles glisten with mixed shades of green, copper, blue, red, and of course gold.

 

The secret to the myriad display of colors is found just below the surface of the beetle’s exoskeleton.  Beneath an outer translucent layer rests stacks of tiny slanting plates that cover color pigments.  Light rays striking the surface of the plates are reflected as a shimmering sheen, while light rays that bounce off the pigments produce various colors.  The result is a lustrous mix of ever-changing hews; a kaleidoscope of colors that are almost unmatched in the insect world.

 

Of course, the beetle’s colorful display isn’t meant to elicit “oohs and ahhs” from humans; it’s meant to signal, “don’t mess with me” to predators.  Using bright colors to send a warning message to enemies is known as “aposematic coloration.”

 

Dogbane (Apocynum spp.) is the representative species for the dogbane family, Apocynaceae, which includes milkweeds and other plants that ooze sticky white sap ladened with poisonous alkaloids (cardiac glycosides).  Indeed, the genus name Apocynum translates to “poisonous to dogs,” or “dog killer.”  Sap from dogbane is reported to have been used at one time against ravenous feral dogs.

 

Dogbane beetles feed on the three dogbanes found in North America:  common or hemp dogbane (A. cannabinum), fly-trap or spreading dogbane (A. androsaemifolium), and intermediate dogbane (Apocynum × floribundum).  Although there are reports in the literature that the beetle feeds on various milkweeds (Asclepias spp.), I’ve scoured milkweeds in Ohio without finding this beetle.  I’ve wondered if perhaps the reports are actually referring to the Cobalt or Blue Milkweed Beetle (C. cobaltinus) that does feed on western milkweeds.  However, this beetle has not been reported in Ohio.

 

Dogbane beetles ingest the poisonous cardiac glycosides in dogbane sap, store the chemicals in specialized glands, and then they secrete the noxious chemical brew when threatened by predators.  Their bright coloration advertises their nasty chemical defense strategy.

 

So, get out and look for dogbane beetles while enjoying the heat!  If you find them, experience the kaleidoscope of colors by viewing the same beetle at different angles to the sun.  They are eye candy … but don’t eat them.

 

 

 

Fruit Cracking of Cherry

Authors Jim Chatfield  Erik Draper

Published on July 1, 2019

 

 

We all know how oppressive the mid-June rains were for many of us in Ohio, but how do you think the sweet cherries felt?  It turns out that excessive moisture is a significant problem for this stone fruit. Fruit cracking from moisture can occur from several causes, from prolonged exposure to too much water in the root zone, but perhaps most likely from continued rainwater on the developing fruits.

 

In areas of northeast Ohio rain and relatively cool temperatures prevailed seemingly every day for weeks recently, including six inches or more in two days. This resulted in continuous water on those fruits with their thin cuticles as the fruit started the early period of ripening. Microcracks in the fruit at this point can expand from water absorption. Periods of rainfall in excess of 1.5 inches are known to enhance such cracking.

 

What can prevent this? In high production areas, intensive management is usually the only way to limit this problem if heavy rains keep coming. This includes drying the fruits in an orchard with airblast sprayers or even helicopters, the use of retractable orchard covers, and use of spraying hydrophobic coatings or osmotic salts multiple times. So, nothing for the faint of heart or pocketbook.  To some extent, this has resulted in increasing sweet cherry production in drier climes. Otherwise, no-rain dances, though this has proved ineffective this year.

 

There are of course other hazards of horticulture for cherry production. Birds can strip the fruit. And Monilinia brown rot may follow cracking, moisture accumulation, and bird damage. The common brown rot disease, caused by the Monilinia fructicola fungus, occurs on stone fruits such as cherry, peach, apricot, plum, and almond (elsewhere) in the genus Prunus¸ with blossom and twig infections leading to fruit rots that result in un-harvestable fruit mummies. Moisture and injury to plant tissue favors disease development. Fungicides and sanitation (rogueing out affected fruit) are control practices.

 

Here are two excellent references for cherry fruit cracking that were used in compiling this bygl-alert:

 

https://www.growingproduce.com/fruits/stone-fruit-avoiding-cherry-fruit-cracking-is-a-balancing-act/

 

https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/em9227.pdf

 

 

BYGL Weekly News for June 24, 2019

The following articles were compiled during the last 7 days by members of the Extension, Nursery, Landscape, Turf (ENLT) team to benefit those who are managing a commercial nursery, garden center, or landscape business or someone who just wants to keep their yard looking good all summer.  Access the BYGL website for additional information on other seasonal topics at: http://bygl.osu.edu

For more pictures and information, click on the article titles.  To contact the authors, click on their names.

Poison Hemlock and Wild Parsnip are going to Seed in Southern Ohio (https://bygl.osu.edu/node/1321)

Authors Joe Boggs and Erik Draper

Published on June 21, 2019

Poison hemlock (Conium maculatum) and wild parsnip (Pastinaca sativa) are two of our nastiest non-native weeds found in Ohio.   Poison hemlock can kill you while wild parsnip may make you wish you were dead.  Both are commonly found growing together and continuously wet conditions caused both to flourish this growing season. The size of some infestations has been remarkable.Poison hemlock and wild parsnip are members of the carrot family, Apiaceae.  The old name for the family was Umbelliferae which refers to the umbel flowers.  They are a key family feature with short flower stalks rising from a common point like the ribs on an umbrella.  In fact, the origins of both umbel and umbrella can be traced to the Latin word umbra which means shadow or shadow.

 

Poison hemlock produces white flowers on stalks that create a more rounded look; perhaps a bit more like an umbrella.  Wild parsnip has intense yellow flowers with the stalks producing a more flat-topped appearance.

Both are biennial weeds meaning that it takes two years for plants to produce seed.  The seeds currently being produced will give rise to plants that spend their first year as low-growing basal rosettes.  The plants produce a long, thick taproot while in this stage.

During their second year, plants “bolt” by producing erect, towering stalks and multi-branched stems topped with umbel flowers.  Mature wild parsnip plants may top 6′ tall while poison hemlock plants can tower to as much as 8 – 10′ tall.  Both are prolific seed producers.
 
Wild parsnip plants have leaves that look vaguely like celery, another member of the carrot family.  Mature plants have a single, thick, deeply grooved, greenish-yellow stem that sprouts lateral branches topped with flowers.
 
All stages of poison hemlock plants have bluish-green leaves that are 3-4 times pinnately compound.  The deeply cut parsley-like leaflets have sharp points.  Flowering plants have hairless, light-green to bluish-green stems that are covered with obvious reddish-purple blotches.  However, the blotches may occasionally coalesce to cause stems to appear an almost solid color.
 

Why Should You Care?

Poison hemlock is one of the deadliest plants in North America.  Plants contain highly toxic piperidine alkaloid compounds, including coniine and gamma-coniceine, which cause respiratory failure and death in mammals. The roots are more toxic than the leaves and stems; however, all parts of the plant including the seeds should be considered dangerous.

The toxins must be ingested or enter through the eyes or nasal passages to induce poisoning; they do not cause skin rashes or blistering.  Regardless, this plant should not be handled because sap on the skin can be rubbed into the eyes or accidentally ingested while handling food.

 

Wild parsnip sap contains psoralens which are naturally occurring phytochemicals grouped in a family of organic compounds known as linear furanocoumarins.  Psoralens kill epithelial skin cells by inserting themselves into the DNA in the cell’s nucleus.  These are the cells responsible for protecting us from long-wave ultraviolet radiation (LWUVR) that bombards us in sunlight.

 

Severe blistering occurs when skin affected by the psoralens is exposed to LWUVR. The synergistic effect is called phytophotodermatitis (a.k.a. Berloque dermatitis) and the burn-like symptoms, as well as skin discoloration, may last for several months.  However, connecting skin blistering to exposure to wild parsnip sap can be a challenge.  The cause and effect are muddled by time because symptoms do not appear for around 24 hours after exposure to LWUVR and severe blistering doesn’t peak for another 48 to 72 hours.

Another challenge is that wild parsnip commonly grows in and around poison hemlock.  Gardeners exposed to wild parsnip growing among poison hemlock may mistakenly blame the poison hemlock for their ultimate misery.

 

It is becoming too late to effectively manage either of these weeds in southern Ohio, but there may still be time to reduce infestations in the central or north parts of the states.  However, it’s important to remember that once flowers mature, seeds will still be produced on plants that have been cut down.

 

While it may be too late for control, it’s not too late to suffer from the toxicity of both of these plants.  They will remain a risk until collapsing later this season.

 

 

Don’t be Fooled

Apiaceae is a large family that includes many innocuous plants.  The roots of wild carrot, or Queen Anne’s lace (Daucus carota), are sometimes eaten raw or cooked.  Unfortunately, they bear a striking resemblance to poison hemlock roots and misidentifications have been responsible for a number of accidental poisonings.

During this week’s BYGL Zoom Inservice, Erik Draper showed pictures of garden angelica (Angelica archangelica) which is sometimes cultivated for its edible roots and stems as well as its perceived medicinal properties.  The stems are a deep purple.  As noted above, poison hemlock stems are commonly covered in reddish-purple blotches, but those blotches may occasionally merge to produce an almost solid color.

 
I never considered fennel (Foeniculum vulgare) to be a possible look-a-like plant for either poison hemlock or wild parsnip.  However, last season, I was told by an avid gardener that while she and a friend were walking along a trail in Ohio, her friend grabbed some poison hemlock seeds thinking they were fennel seeds.  Thankfully, the gardener stopped her friend from eating them.
 

Crabs, Scab and then So Sad… Drab! (https://bygl.osu.edu/node/1320)

Authors Erik Draper and Joe Boggs

Published on June 20, 2019

On the BYGL conference call, I shared that I am amazed at how the foliage of the greatest landscape small tree, the breathtaking crabapple, has remained relatively clean here in NE Ohio.  I was expecting with all of the rain this year, that we would quickly see what we Crabarians affectionately term “year of the scab dog”.  This “scab dog” effect is due to the fungal pathogen (Venturia inaequalis) causing extensive apple scab lesions on susceptible crabapple tree leaves.  Given our perfect environmental conditions for this fungal disease, I expected it to quickly overwhelm and wreak havoc on crabapples and the genus Malus, which includes eating apples.  Infected leaves turn yellow or other fall-type colors, then begin dropping to the ground like rain, resulting in unmistakable tree nudity, thereby rudely creating the “scab dog” tree.

 
Our southern correspondent, Joe Boggs, again exclaimed his dismay “on how could this be possible when trees he was seeing, were literally covered in scab”.  I quickly retorted that it was due to the Northern part of Ohio is just more elite plant-wise!!  Apple scab lesions are a fuzzy, drab, olive gray-green in color and range from distinct lesions to covering the entire leaf surface.
 
While I was elated there did not appear to be any apple scab lesions yet, I am confident that it is only a matter of time before symptoms begin to show up.  In fact, Jim Chatfield was quiet and when asked why so quiet, he said he was waiting for some crazy statement like “maybe there aren’t any infections!”  Jim reminded us about latent infections, which are infections that have already occurred in the leaf, but are as of yet, symptomless!
 
Joe reminded us there are other diseases that can also cause crabapple leaves to turn yellow and fall off.  The disease that comes to mind is one that can also create some confusion because it can affect apple scab resistant crabapples!  Frogeye leaf spot, caused by the fungal pathogen, Botryosphaeria obtusa, is one that closely mimics apple scab symptoms.  The main difference is the appearance of the lesions on the leaf.  Frogeye leaf spots are small circular lesions with a distinct purple border and the interior of that lesion is beige in color, creating its namesake eye spot appearance.
 
Next time you notice leaves falling off your lovely crabapple, look closely at any lesions on the leaves will help you to determine which fungus might be causing the problem on your tree.
 

The Natural…and Unnatural History of Trees (https://bygl.osu.edu/index.php/node/1319)

Authors Jim ChatfieldPublished on Junes 20, 2019

Our Tuesday, July 9 program, from 10:00am to 4:00pm will largely be a Walking and Talking program as we explore Secrest Arboretum trees.  Trees as you know them (in the 110 acres of the main part of the Arboretum) and the Secrets of Secrest that you may not know – in the part cut off by the highway decades ago. In fact you shall receive a prize if you know the year when this pruning of the Arboretum occurred.

We will explore a cultivated Arboretum and we will also explore forested areas in the older Arboretum section – and we shall see what happens when cultivated plots are abandoned over the years. Which plants invade, Arboretum plants and the run of invasives. We will even see, or at least speculate upon, which plant seeds arrived in the older sections in a hurry following the Secrest Tornado of 2010.

 
Come see Canaan fir plantings. Super Sweet maples. Black walnut plots. Exotic firs. Evidence of Johnny Paulownia? Will you traverse the under-highway portal the ArbMouth connecting the two Arboreta or walk more traditional routes?
 
We will start from the new Arboretum Center at Secrest, have some samples laid out at the Arboretum Pavilion, and lunch in the main Arboretum. Other than that, we shall be outside, and as co-program creator and presenter arborist Al Shauck notes: “There will be plenty of walking involved in some woody areas. Bring bug repellant and sunscreen.”  We will have these available too, but your walking shoes will be – on you.
 
As Al writes: “The Secrest Arboretum in Wooster gives us a chance to see how humans and nature interact to define our environment.  Join James Chatfield, Nathan Ames and Al Shauck in a tour into secret areas of Secrest seen by only a few and discover how natural and unnatural progression play out to change ecosystems.”
 
Topics include:

 

Invasive Species

Plant ID

Pest and Disease ID and Management Strategies

Cultural Environmental Problems and Issues

The “Natural” and “Managed” Environments

Natural History Musings

The program is sponsored by Ohio State University Extension, Secrest Arboretum, and The Ohio Independent Arborist Association. The cost is $25. Registration is available at go.osu.edu/chatfield (mThe “c” in chatfield must be lower case for the site to work – I am very modest) and will be $25.  You can contact Sarah Mays of OSU Extension at mays.201@osu.edu or 330-263-3831, fax: 330-263-3667

 

There will be an assortment of professional horticultural and arboricultural certification credits available.

Other Upcoming OSU Extension Secrest Arboretum Schools to come include:

  • Plant Families III: To be rescheduled from July 2.
  • “Bugs”: The Good, The Bad, and the Bizarre, August 27.
  • “Sustainable Landscaping”, September 3.
  • “Ohio Plant Diagnostic Workshop”, September 6.
  • “The Sestercentennial of Alexander von Humboldt’s Birth”, September 13-14.
  • “Fall Fungal Fest”, October 10.
  • “ArborEatUm”, October 22.
  • “Fall ArboReadUm”, Date TBA.
  • “Why Trees Matter Symposium”, October 31. At the College of Wooster.


The clearest way into the Universe is through a forest wilderness.” – John Muir.

The most dangerous worldview is the worldview of those have not viewed the word.” – Alexander von Humboldt.

Dogwoods Are Dazzling

Authors Erik Draper

Published on June 19, 2019

 

Kousa Dogwood in Bloom

 

While on our BYGL conference call, I shared the glorious status of Kousa dogwoods (Cornus kousa var. chinensis) right now in NE Ohio.  Only one word can describe them, “OUTSTANDING”!!  Then Joe Boggs from the southern reaches of the state, asked me to repeat what I said about the Kousa’s here.  I told him that they were just reaching their full glory and were unbelievable due to the cooler weather and moisture.

 

Joe then laughed and that he just wanted to make sure about what I had said, because their Kousa dogwood blooms were long gone!  It is always a good reminder that from one end of the state to the other, the difference in weather conditions and plant material in bloom is often astounding!

 

So for Joey and all others who blew through the Kousa bloom this year, you can just enjoy them again in pictures, while I enjoy them in person!

 

 

 

Periodical Cicada: Rounds 1 and 2

Authors Joe Boggs

Published on June 18, 2019

 

Periodical Cicada

 

Brood VIII (Eight) of the 17-year periodical cicadas (Magicicada spp.) have made their presence known in parts of northeastern Ohio, western Pennsylvania, and the northern panhandle of West Virginia.  As with past brood emergences, the overall geographical distribution is spotty; however, there are localized pockets with heavy cicada activity.

 

The general impact of a periodical cicada emergence can be divided into two “rounds.”  Round 1 starts with the emergence of huge numbers of males and females from the soil where they took 17 years, or 13 years for some broods, to develop.  The males then “sing” to attract females for a love tryst.  A behavior known as “chorusing” occurs when males synchronize their singing which tests the nerves of besieged homeowners.  In short, a full-blown periodical cicada brood emergence is not subtle.

 

Mated females then use their spade-like ovipositors (ovi = egg, positor = deposit) to create slits and insert eggs into tree stems.  This initiates Round 2 which is defined by the short-term and long-term damage caused by periodical cicadas.  Although periodical cicadas have piercing-sucking mouthparts just like their aphid cousins, they cause no noticeable damage from their feeding activity.

 

The physical injury to the vascular and structural tissues of tree stems usually cause the affected stems to break-off and fall to the ground.  This may happen immediately with attached leaves remaining green.  Or, the stems may remain attached long enough for the leaves to dehydrated, wilt, and turn various shades of brown producing a symptom called “flagging” because it looks like small flags tied to the ends of the branches.

 

The cicada eggs hatch after a few weeks.  The ultimate goal for the newly hatched first instar nymphs is to burrow into the soil to spend the next 17 years (13 yrs. for some broods) imbibing juices from tree roots.  It is believed that twig detachment supports greater success and survival of the nymphs on their journey to the soil.

 

If heavy damage produced by the ovipositing females causes twigs to break-off and fall to the ground, the first instar nymphs just need to step-off into the soil.  However, if twigs remain attached, the nymphs must drop from the tree canopy in a leap of faith aiming to land on soil that covers tree roots and not be blown off-course to drop onto a pasture, lake, parking lot, southbound freight train, etc.

 

The flagging may remain on the trees long after the cicadas are dead and gone.  In fact, after Brood V emerged in 2016 which included a large part of eastern Ohio, I received e-mail messages well into August from Ohioans who had traveled I-70 asking why the oaks were looking so bad.  It was cicada flagging damage that had never detached.

 

Cicada oviposition injury that was not severe enough to cause flagging may remain apparent for many years to produce diagnostic challenges.  This is demonstrated by the images below.

 

Of course, the actual tree damage caused by periodical cicadas is considered minimal. It’s long been recognized that although the flagging is very apparent, it causes no real harm to the overall health of established trees.  In fact, it could be considered “natural pruning.”  Consider that periodical cicadas and their tree hosts have been living together for tens of thousands of years, and yet we still have trees.

 

 

 

Magnolia Scale is Puffing-Up and Dripping Honeydew

Authors Joe Boggs

Published on June 18, 2019

 

Magnolia Scale

 

Magnolia scale (Neolecanium cornuparvum) females are “puffing-up” and dripping copious quantities of honeydew in southwest Ohio.  This native scale has a strong affinity for non-native magnolias and associated hybrids.  Common hosts include star magnolia (Magnolia stellate), lily magnolia (M. liliiflora), and saucer magnolia (Magnolia × soulangeana).  Native magnolias are more resistant perhaps because of natural defenses that developed through a shared evolutionary history with the scale.

 

Magnolia scale is a type of “soft scale” so named because of the helmet-like soft leathery covering that protects the females.  Although it’s one of the largest soft scales in Ohio with mature females measuring as much as 1/2″ in diameter, the current pinkish-tan colored females are still somewhat flattened and may be obscured by a heavy coating of white, waxy, flocculent material.

 

Life Cycle

Magnolia scale has one generation per season.  Females and males spend the winter as first instar dark-colored nymphs attached to the stems of their host plant.  Their resemblance to lenticels makes them inconspicuous.  The nymphs mature in the spring with the males developing into small gnat-like insects that fly to females and mate.

 

The females remain immobile but rapidly expand in size as they mature through the spring and summer.  Eggs are produced in late summer to early fall and held internally until they hatch creating the illusion that the females are giving birth to the first instar nymphs (= crawlers).  The first instar crawlers are highly mobile but become immobile once they insert their piercing-sucking mouthparts into stems.  This is the overwintering stage.

 

Impact

Magnolia scale adults and nymphs insert their piercing-sucking mouthparts into phloem vessels to tap plant sap.  A substantial loss of sap from a heavy scale infestation represents a serious loss of energy resources to the trees.  The associated physiological stress can produce leaf yellowing and loss, branch dieback and canopy thinning; even the death of entire trees.  Stress can also indirectly make trees susceptible to other problems.

 

Magnolia scale sucks plant sap to withdraw carbohydrates which provide energy and to extract amino acids which are building blocks for proteins.  However, the sap contains trace amounts of amino acids compared to huge amounts of dissolved carbohydrates.  This means the scale must process a large amount of sap to extract the small amount of amino acids.  They discharge the excess sugar-rich liquid from their anus in the form of a sticky, sugar fluid called “honeydew” which is actually a nice name for scale diarrhea.

 

Magnolia scale is a prolific honeydew producer.  During normal years, the sticky honeydew drips onto the leaves and stems of the host plant as well as understory plants to eventually become colonized by black sooty molds.  Although the molds do no harm, blackened leaves can seriously reduce the aesthetic appeal of heavily infested trees.

The honeydew also attracts a plethora of freeloading sugar-sippers including bees, wasps, ants, and flies.  In fact, a high percentage of the flies are often members of the blowfly family, Calliphoridae.  Their maggots may have a taste for decaying flesh, but adults like sweets.

Thus far, this season has not been normal in southwest Ohio.  Recurring periods of heavy rainfall appear to be keeping pace with scale honeydew production.  Several heavily infested rain-washed magnolias that I inspected recently had little evidence of honeydew on the leaves and no black sooty patina.  In fact, given how often I use black sooty molds as a scale (or aphid) indicator, I may have missed the infestation had I not already known the trees were loaded with scale.  Of course, the magnolia scale will continue to pump-out honeydew for the better part of the summer, so conditions can quickly change.

Management

Magnolia scale infestations attract a wide range of natural enemies such as the notorious scale and aphid nemesis:  the multicolored Asian lady beetle (Harmonia axyridis) with their alligator-like larvae.  Sigil lady beetles (Hyperaspis spp.) and Australian mealybug destroyers (Cryptolaemus montrouzieri) may also show-up to chow down on magnolia scales.  Both have wool-coated larvae that are actually wolves in sheep’s clothing.

This bio-allies can have a significant impact on maintaining magnolia scale infestations below noticeable levels on native magnolias.  Unfortunately, they appear to have a limited effect on magnolia scale populations on non-native magnolias.  It’s speculated that the lack of defenses by the non-native trees may support such a rapid scale proliferation, the large numbers simply overwhelm the ability for natural enemies to have a significant effect.

This means other management tactics may be necessary to support plant health.  A direct approach is to use physical removal.  If trees are small and scale populations are low, a dish scrubber or bathroom scrub brush can be used to physically remove the females before they produce eggs at the end of summer.

Topical insecticide applications targeting 1st crawlers later in the growing season can be effective.  However, the extended period of egg hatch presents a serious challenge and requires multiple applications with thorough coverage of the stems.  This is particularly true for “horticultural oils” (e.g. summer oils).  Thorough coverage is critical because oils only kill on contact. Spring applications can also be effective; however, there is a risk for damaging flower buds.

Control can be achieved with single applications of the neonicotinoid systemic insecticides imidacloprid (e.g. Merit) and dinotefuran (e.g. Safari).  There are two effective “treatment windows” in Ohio.  They are late summer to early fall, before settled crawlers stop feeding for the season, or sometime in May after overwintered nymphs start feeding.  However, spring applications should be delayed until after trees have finished flowering to avoid killing pollinators.  Of course, as with all insecticide applications, it is critical to read and follow label directions.

 

BYGL Weekly News for May 20, 2019

The following articles were compiled during the last 7 days by members of the Extension, Nursery, Landscape, Turf (ENLT) team to benefit those who are managing a commercial nursery, garden center, or landscape business or someone who just wants to keep their yard looking good all summer.  Access the BYGL website for additional information on other seasonal topics at: http://bygl.osu.edu

 

For more pictures and information, click on the article titles.  To contact the authors, click on their names.

 

 

Rhododendrons – Azaleas; Reality Art!

Authors Thomas deHaas

Published on May 20, 2019

 

 

Rhododendrons – Azaleas; Reality Art!

 

Rhododendrons and Azaleas are blooming in Northeast Ohio. They come in almost all the colors of the rainbow! Azaleas have been blooming in northeast Ohio since April 8th starting with Cornell’s Pink, a deciduous Azalea variety.

 

The first of the evergreen Rhododendrons to bloom was Rhododendron PJM, which was in full bloom April 19th. Rhododendron Olga Mezzit followed on April 22nd (But this was in Columbus).

 

Our Rhododendron in Northeast Ohio are just coming into bloom like Rhododendron Yaku Princess which starts pink as a bud but opens white.

 

Now in mid-May, Evergreen Azaleas are in full bloom like Azalea Herbert, a lavender and Azalea Stewartsonia, a bright Red.

 

Rhododendron English Roseum and Rhododendron Roseum Elegans are also blooming.

 

However, don’t forget the deciduous Azaleas calendulaceum – Flame Azalea and Azalea Klondike with yellow flowers.

 

Just remember, Right plant, right place. Rhododendrons and azaleas thrive in moist, well-drained slightly acid soil and prefer partial shade or protection from add day direct sunlight.

 

Enjoy nature’s artistic rainbow of colors.

 

 

 

 

Yellow Fields Forever

Authors Joe Boggs

Published on May 18, 2019

 

 

The dichotomous nature of cressleaf groundsel (a.k.a. butterweed) (Packera glabella; syn. Senecio glabellus) tests the tolerance of lovers of native wildflowers.  On one hand, a sea of golden-yellow flowers carpeting farm fields in Ohio provides welcome relief from highway monotony.  On the other hand, upright 2 – 3′ tall plants dominating Ohio landscapes presents a weed management challenge.

 

Cressleaf groundsel is so-named because its lower leaves resemble watercress.  Its alternate common name of butterweed comes from its conspicuous buttery yellow flowers.

 

Cressleaf goundsel is a winter annual meaning that seeds germinate in late summer to early fall.  Members of this sneaky group of weeds grow throughout the winter and flower in the spring.  Winter annuals aren’t much of a problem for farmers who plow in the spring because entire plants are plowed under.  However, cressleaf groundsel growing in hay fields is a different matter.

 

The leaves, stems, flowers, and seeds contain pyrrolizidine alkaloids that can cause liver damage if consumed by livestock.  The resulting chronic disease is called “seneciosis” from the alternate name for the genus.  Normally, livestock will avoid eating cressleaf groundsel; however, they may accidentally ingest dried plants if the plants or plant parts are harvested with hay.

 

A close look at the golden-yellow cressleaf groundsel clearly shows why it’s a member of the aster family (Asteraceae).  Each flower has a central composite cluster of disc flowers surrounded by up to 15 florets radiating like a star.  Indeed, “aster” comes from the Greek name for “star.”

 

The flowers are borne at the ends of thick, erect, deeply ridged green stems that are sometimes streaked in reddish-purple.  Seedheads look like miniature dandelion puff-balls which is no accident; dandelions (Taraxacum spp.) also belong to the aster family.

 

Vast expanses of cressleaf groundsel in full flower may draw the misplaced ire of allergy sufferers.  However, if you’re suffering sneezing fits, the answer, my friend, isn’t blowin’ in the wind.  The sticky, large pollen grains are too heavy to be moved by anything other than insects.  Cressleaf groundsel is actually considered to be an important early spring source of nectar for bees and other pollinators.

 

A Word from Management

Winter annuals can become a serious problem for landscape and nursery managers created by an over-dependence on pre-emergent herbicides applied in the spring to control weeds.  Preemergent herbicides used to target the spring seeds of summer annuals (e.g. crabgrass) do not remain effective long enough to suppress winter annual seed germination.  This allows winter annuals to escape to reappear as unwelcomed harbingers of spring each year.

 

Of course, if cressleaf groundsel is misbehaving, this winter annual can be easily removed right now and seed production reduced by hand-pulling or cultivation.  “Burn-down” herbicides such as pelargonic acid (e.g. Scythe) are also effective.

 

However, various reports indicate cressleaf groundsel may have some tolerance for glyphosate (e.g. Roundup), so high rates are required.  Indeed, there is speculation that perhaps the rise of cressleaf groundsel in recent years has occurred through herbicide-induced “un-natural selection.”  In other words, one person’s weed management program is another person’s wildflower proliferation program.

 

Another Yellow Flower Rocketing Skyward

The yellow-flowering garden yellowrocket (Barbarea vulgaris) is a non-native invasive biennial weed that is also on the rise at this time of the year and may be found mixed with cressleaf groundsel.  Yellowrocket belongs to the mustard family (Brassicaceae), so it is a prolific seed producer.

 

Plants spend the first year in the vegetative stage as tightly clustered rosettes of prostrate leafy stems that are often hard to spot lurking beneath other plants.  The weed shows its true colors the second year when it enters the reproductive stage.  Abundant clusters of tiny, bright yellow four-petaled flowers borne atop hairless, stout, light green to reddish purple flower stalks appear to “rocket” above 1-2′ tall rounded, bushy plants.

 

 

 

 

Fiery Eye-Candy

Authors Joe Boggs

Published on May 17, 2019

 

 

I came across one of the most striking beetles today that you’ll ever find in Ohio.  The fittingly named Fiery Searcher Caterpillar Hunter (Calosoma scrutator) is best described as beauty with a bite.

 

Their beauty is clearly on display with deeply grooved metallic green elytra edged in lustrous reddish-orange.  The elytra are actually hardened front wings that protect the abdomen and membranous hind wings.  All beetles share this general body plan as described in the name Coleoptera:  coleo = sheath; ptera = wing.

 

The eye-candy continues with a dark blue prothoracic shield that is edged by a radiant ring of copper-orange.  This flame-like motif is responsible for the “fiery” in the common name.

 

However, I believe the most colorful display is revealed by flipping the beetle over to expose a carnival glass-like mix of green and reddish-copper that plays off the vibrant colors of the long legs best described as dark blue fading into electric-violet.  You need a color-wheel to give accurate names to the range of colors displayed beneath this colorful beetle.

 

The bite of this predacious beetle comes from their powerful, sickle-shaped mandibles.  Fiery searchers hunt down and feast on free-range caterpillar meat as well as any other soft-bodied insect they can clamp their mandibles on; thus the “caterpillar hunter” part of their common name.

 

Fiery searcher caterpillar hunters live for 2 to 3 years spending the winter beneath bark or in the soil.  They are one of the largest “ground beetles” (family Carabidae) found in Ohio measuring around 1 1/4″ in length.  These large meat eaters are one of our more significant insect predators with the capability of having a substantial impact on the population densities of general defoliators.

 

Their large size and obvious hunting equipment which includes long legs, big eyes (The better to see you with, my dear!), as well as obvious mandibles (The better to eat you with, my dear!) makes the fiery searcher a perfect model for teaching about insect predators.  Of course, you should use pictures, not live specimens because they bite.  They’re miniature wolves after all.

 

 

 

 

The European Paper Wasp Conundrum

Authors Joe Boggs  Curtis E. Young  Dave Shetlar

Published on May 17, 2019

 

 

European paper wasps (Polistes dominula) have presented a conundrum over the past several years in Ohio.  The literature notes these wasps were first found in North America in the 1970s near Boston, MA.   They are now found throughout much of the U.S. and parts of Canada.

 

These highly aggressive colonizers exploded onto the Ohio scene between 2000 and 2010 to become the dominant paper wasp found in our state.  They were a frequent topic during our weekly BYGL conference calls with Dave Shetlar and Curtis Young reporting high populations in central and western Ohio and I commonly found them in Greater Cincinnati.

 

In fact, we had real concerns this non-native would eventually supplant our native wasps including the northern paper wasp, P. fuscatus, and the native wasp, P. annularis.  At one point, it became difficult to find these native wasps.

 

However, the reverse has become true in recent years.  I talked with Dave and Curtis to compare notes and we’ve all observed the same thing.  Our native paper wasps have become more common, but the European papers wasps are becoming harder to find.  We have no explanation for the apparent reversal of fortune for the European interlopers.

 

That’s why I was so surprised to find the nest that’s pictured in the lead image for this Alert in a local park this past Wednesday.  In fact, the wasps almost found me!  The nest was at eye-level, but I didn’t notice them until I was only about a foot away.

 

My concern was justified.  European paper wasps gained a deserved reputation for being very aggressive.  This coupled with their propensity to build nests in locations where we generally don’t find native paper wasps, such as in dense shrubbery, inside railings and mailboxes, and inside the bases of light poles, frequently brought them into stinging conflicts with people.

 

However, the European invaders do share several traits with our native paper wasps.  Winter is spent as fertilized females in protected locations.  The lone over-wintered females start building their paper nests in the spring.  They use their powerful mandibles to grind-up fibers gathered from dead wood and plant stems which they mix with their saliva to extrude the water-resistant paper used to construct their nests.  They are soon joined by their off-spring including new queens which all join in to gather food and expand the nest.  They only use their paper nests for one season and new nest-building is occurring right now.

 

As with our natives, the European paper wasps are both pollinators and predators.  They are frequently found visiting flowers.  Look closely at the soon-appearing blooms of bottlebrush buckeye (Aesculus parviflora) and later in the season at the blooms of common goldenrod (Solidago canadensis).

 

They also gather and grind-up various “meat items” with their powerful mandibles to provide a protein-rich slurry to their helpless grub-like young developing in the paper nest cells.  The meat may include caterpillars, sawfly larvae, and other soft-bodied insects which makes them important predators.  In fact, some researchers have noted the Europeans may have a wider meat palate compared to our natives which could account for their rapid population expansions at the expense of our natives.

 

Please Report Your Observations

 

We would like to gauge the current status of European paper wasps in Ohio as well as elsewhere.  However, we need your help.

 

We would like for you to be on the lookout for these non-natives, but please note that European paper wasps bare a remarkable resemblance to yellowjackets; they are paper wasps wrapped in yellowjacket clothing.  In fact, their black and yellow markings caused them to be frequently mistaken for yellowjackets.  However, yellowjackets tend to be smaller with shorter legs and more robust bodies.  They also construct enclosed paper nests rather than the open nests built by paper wasps.

 

If you observe European paper wasps, please drop me an e-mail message with the exact location, the situation (nest or wasp), and an estimated number such as “several on a nest” or “lone wasp on flowers.”  Pictures would be hugely helpful … if you can safely take them!

 

Just click on my name at the top of this Alert to get my e-mail address.

 

 

 

Tree of the Week – Carolina Silverbell

Authors Amy Stone

Published on May 17, 2019

 

 

Carolina silverbell (Halesia carolina) in bloom is a sight to behold. Its delicate white bell-shaped flowers hang down from 1/2 to 1 inch stalks in 2 to 5 flower clusters. While you can enjoy at all angles, my favorite is from underneath looking up as shown in the photo below.

 

As the spring progresses, flowers fall to the ground below carpeting the ground with the white flowers. The fruit that appears is oblong, 4-winged, dry drupe that will persist into the fall and occasionally into the winter.

 

This tree is a medium grower and will usually top off at 30 – 40 feet tall and 20 – 35 feet wide. The national champion tree is located at the Great Smokey Mountains National Park in Tennessee and is over 100 feet tall and 40 feet wide.

 

The plant does prefer a rich, well-drained soil with a pH range of 5 to 6, high in organic matter. Leaves can become chlorotic in high pH soils. The tree will do well in sun or part-shade.

 

More Information

Missouri Botanical Garden, Plant Finder

http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kemp…

University of Kentucky

http://www.uky.edu/hort/Carolina-Silverbell

Illinois Wildflowers

https://www.illinoiswildflowers.info/trees/plants/car_silverbell.html

 

 

 

Bladdergall Enlightenment

Authors Joe Boggs

Published on May 16, 2019

 

 

My introduction to the wonderful world of plant galls began with observing vibrant red, wart‑like galls, known as “bladdergalls,” adorning the upper leaf surfaces of a silver maple tree.  The galls consist entirely of plant tissue and are produced under the plant gene-manipulating direction of the Maple Bladdergall Mite, Vasates quadripedes (family Eriophyidae).  I’m probably not alone with this being the first gall ever encountered.

 

Of course, mine is a cautionary tale.  I did not know that maple bladdergalls are a gateway-gall; they can lead to a serious hard-core gall-addiction.  It took me years to muster the courage to say this:  my name is Joe Boggs and I’m a gall-oholic.

 

The eriophyid responsible for maple bladdergalls only produces this type gall and no other.  The equally common maple spindle galls, which are sometimes called nail galls, are produced by a different eriophyid mite, V. aceriscrumena.  This eriophyid mite species never produces bladdergalls.

 

Maple bladdergalls have been great teachers of gallology.  The first lesson I learned is that galls can change appearance as they age, or “mature.”  The maple bladdergalls change from bright green to deep red and eventually turn black.

 

The second lesson is that populations of plant gall-makers tend to rise and fall dramatically from year-to-year.  I often re-visit the same trees year after year and I’ve found that while a tree may reward me with a huge gall display one year, it frequently disappoints the next.  My maple bladdergall photos below demonstrate this; same tree, different years.

 

Finally, very few galls that are produced by insects and mites cause any real harm to the overall health of their host plants.  I sometimes get reports of maple bladdergalls causing defoliation.  However, I’ve never observed this first-hand.  I suspect reported defoliation is perhaps connected to other issues including poor site conditions (e.g. poor drainage), nutrient deficiencies, maple anthracnose, maple petiole borer, etc.  One of the most common diagnostics missteps is to blame the obvious.

 

Other Eriophyid Gall Oddities

The Black Tupelo Bladdergall Mite (Eriophyes nyssae) produces galls that look very similar to those found on maples.  Black Tupelo (Nyssa sylvatica) (a.k.a. black gum, sour gum) provides a twofer with the eriophyid, Eriophyes dinus, producing crinkled leaf edges.  The crinkling is sometimes referred to as Black Tupelo Leaf Roll Galls.

 

One of my favorite plant galls is produced by the Poison Ivy Bladdergall Mite (Aculops rhois (= A. toxicophagus)) on its namesake host.  The galls vaguely resemble the itchy skin blisters we suffer when we contact the plant.  I like to imagine that gall-infested poison ivy plants suffer the same agonizing itch, but they have no fingers!

 

I’ve found that boxelder (Acer negundo) can challenge the saying “leaves of three, leave it be,” and the handiwork of the Boxelder Bladdergall Mite (Eriophyes negundi) doesn’t help.  The galls bear a striking resemblance to those on the three leaflets of poison ivy.  However, the boxelder bladdergalls undergo a distinctive change in appearance as they “mature.”

 

Early on, they appear as small bladdergalls.  Later, they become much larger and produce velvet-like patches on the corresponding lower leaf surface.  They are even given a different common name of “Boxelder Velvet Galls.”  I originally thought bladder and velvet galls were the work of two different gall-makers, but the literature attributes both types of galls to the same eriophyid mite.

 

Galls produced by the eriophyid, Eriophyes brachytarsus, are another type bladdergall that changes form as they mature.  At first, the galls look like typical bladdergalls and are called “walnut bladdergalls” in some online references.  However, as they mature, the galls become distinctively pouch-like and are referred to as “walnut pouch galls.”  Eventually, the galls break open like popcorn to reveal tufts of silvery-white hairs.

 

I first encountered the fuzzy, cauliflower-like galls produced by the eriophyid, Aceria cephalanthi, on common buttonbush (Cephalanthus occidentalis) last year in northeast Ohio.  I could find no information in the literature about this gall-maker.  However, given the rise of buttonbush as a prized bumble bee magnet in pollinator gardens, I predict this gall will gain greater notoriety.

 

As with the vast majority of plant galls produced by arthropods (e.g. wasps, midges, etc.), those that are induced by eriophyids cause little to no harm to the overall health of their plant hosts.  Indeed, I contend that they add ornamental value to their tree and shrub hosts.  Of course, I’m a gall-oholic.

 

 

 

Slugged Rose Leaves from a Bristly Pest

Authors Joe Boggs

Published on May 16, 2019

 

 

When I started working for Extension back when growing roses meant hybrid teas, the dominant roseslug sawfly (order Hymenoptera, family Tenthredinidae) was Endelomyia aethiops.  It was so common, the common name approved by the Entomological Society of America (ESA) for this species was simply Roseslug.

 

The roseslug only has one generation per season, so we didn’t worry too much about this sawfly.  The early-season leaf damage was quickly covered over by new leaves as the season progressed.  We would occasionally see the Curled Rose Sawfly (Allantus cinctus), but with only two early-season generations, this sawfly would come and go so quickly it seldom caused appreciable damage.

 

However, in recent years, these relatively innocuous sawflies have been largely supplanted in Ohio by the more damaging Bristly Roseslug Sawfly (Cladius difformis) which has multiple generations per season.  Damage from this sawfly starts in the spring and only ends with the first frost.  The expanding numbers with each new generation may produce heavy defoliation by the end of the season.

 

I’m not sure what changed.  The bristly roseslug sawfly is considered a European native that was accidentally introduced into North America.  However, the introduction probably occurred decades ago because it is now found through the continent.  Of course, one thing that changed during this time was the rise of shrub roses over hybrid teas as the dominant roses in Ohio landscapes.  I don’t know of any host preference studies on this slug sawfly; however, there seems to be some preference for the shrub roses.

 

Early instar bristly roseslug larvae feed by removing one leaf surface and the mesophyll beneath. The corresponding epidermis on the opposite leaf surface remains intact and turns white producing a characteristic “windowpane” symptom.  Eventually, the “windowpanes” drop out to produce holes.

 

Later instars feed between the main veins to directly produce holes in leaves.  Heavy feeding damage by early and late instars may combine to produce “see-through” leaves.  We have commonly observed this type of damage from bristly roseslugs over the past few years in southwest Ohio.

 

You must look closely to spot the pale green semi-transparent sawfly larvae.   Despite their common name, the larvae of roseslug sawflies resemble tiny caterpillars and look nothing like the glistening, elongated pear-shaped “slug sawflies” which do resemble tiny slugs.  As their common name indicates, bristly roseslug sawfly larvae are covered with short, hair-like bristles that can be best seen with a hand-lens.

 

Control and prevention of further damage depend on proper identification of the true culprit.  Only the bristly roseslug is worthy of control measures because it continues to produce damage throughout the season.

 

Biorationals such insecticidal soaps are effective, but direct contact is necessary.  Products containing spinosad (e.g. Conserve, Entrust) are effective against sawfly larva and will also have less impact on bio-control agents.  Chlorantraniliprole (e.g. Acelepryn) is also effective and presents a low risk to pollinators.  Soil drench applications of systemic insecticides such as imidacloprid (e.g. Merit) or dinotefuran (e.g. Safari) are effective and provide lengthy protection.

 

Although roseslug larvae look like caterpillars, products based on strains of the bacterium Bacillus thuringiensis (Bt) that are specific to controlling moth caterpillars (order Lepidoptera) will have no effect on these primitive hymenopteran larvae.

 

 

 

Sycamore and Ash Anthracnose

Authors Joe Boggs

Published on May 16, 2019

 

 

Symptoms of two host-specific fungal anthracnose diseases are becoming apparent in southwest Ohio.  Ash anthracnose is usually announced by the appearance of irregularly shaped reddish-brown, blotchy spots along the edges of the leaflets.  The leaf necrosis often causes the leaflets to curl and severe infections may lead to defoliation.

 

Sycamore anthracnose typically takes two forms:  leaf lesions that appear to “bleed” from the veins and stem cankering that causes new leaves to wilt and blacken.  Both forms can lead to defoliation.  Thus far, the symptoms associated with the stem cankers has been the most apparent form of this disease in southern Ohio.

 

It’s important to keep in mind that the fungal anthracnose diseases affecting sycamore and ash are produced by different host-specific fungi.  The fungus that produces anthracnose on sycamore does not infect ash and vice versa.  This is also true for other fungal anthracnose diseases such as those that may occur on maple, oak, and beech.  Each is caused by a host-specific fungus.

 

Anthracnose diseases occur every year but most are enhanced by cool, wet conditions during leaf emergence.  Of course, “cool and wet” describes the weather experienced throughout much of Ohio this spring.  Still, it is just as common in the southwest part of the state to find sycamores and ash trees that are free of anthracnose symptoms as it is to find trees showing heavy symptoms.

 

Anthracnose diseases are not considered tree killers.  In fact, they seldom cause enough damage to seriously harm the overall health of their host trees.  While affected trees may look bad now, based on past history, the trees will recover.  There’s plenty of time for healthy trees to produce new leaves when warm temperatures are less supportive of new infections.

 

For this reason, it’s difficult to justify making fungicidal applications to suppress sycamore or ash anthracnose.  Sprays applied now cannot undo the damage from the early springs infections responsible for the symptoms we’re seeing now.  Preemptive suppression sprays starting at bud break can reduce infections; however, there’s no way to predict whether or not subsequent spring environmental conditions will support the levels of infection that justify the applications.  While there’s no such thing as an anthracnose crystal ball, history teaches us that heavy infections are a rarity.

 

 

 

Be Alert to Wild Parsnip!

Authors Joe Boggs

Published on May 15, 2019

 

 

Second-year wild parsnip (Pastinaca sativa, family Apiaceae (= Umbelliferae)) plants are producing deeply grooved flower stalks topped by characteristic bright yellow blooms in southern Ohio.  Landscape managers and gardeners should exercise extreme caution around this non-native invasive biennial plant.

 

Wild parsnip sap contains psoralens which are naturally occurring phytochemicals grouped in a family of organic compounds known as linear furanocoumarins.  Psoralens kill epithelial skin cells by inserting themselves into the DNA in the cell’s nucleus.  These cells are responsible for protecting us from long-wave ultraviolet radiation (LWUVR) that bombards us from the sun.

 

Severe blistering occurs when skin affected by the psoralens is exposed to LWUVR. The synergistic effect is called phytophotodermatitis(a.k.a. Berloque dermatitis) and the burn-like symptoms, as well as skin discoloration, may last for several months.  However, connecting skin blistering to exposure to wild parsnip sap can be a challenge.  The cause and effect are muddled by time because symptoms do not appear for around 24 hours after exposure to LWUVR and severe blistering doesn’t peak for another 48 to 72 hours.

 

Another challenge with connecting the dots is that wild parsnip commonly grows in and around other weeds, particularly poison hemlock (Conium maculatum) which is another member of the Apiaceae family.  This deadly non-native biennial weed contains highly toxic piperidine alkaloid compounds which cause respiratory failure and death in mammals.

 

The poison hemlock toxins have a completely different mode of action and must be ingested or enter through the eyes or nasal passages to induce poisoning; they do not cause skin rashes or blistering.  However, gardeners exposed to wild parsnip growing among poison hemlock may mistakenly blame the poison hemlock for their ultimate misery.

 

Psoralens are found in a number of other members of Apiaceae family including the notorious giant hogweed (Heracleum mantegazzianum) which has captured national attention in the past.  However, giant hogweed has only been confirmed in Ohio growing in the extreme northeastern part of the state primarily in and around Ashtabula County.  Wild parsnip is found throughout the state and is equally damaging.  Of course, giant hogweed has a more threatening sounding common name; wild parsnip just sounds like a vegetable gone wild.

 

Wild parsnip is native to Eurasia and grows as a biennial in Ohio requiring two seasons to complete its life cycle.  Plants spend the first year as rosettes with leaves confined to growing from a short stem only a few inches above the ground.  While in this stage, the plant produces a long, thick taproot.  Flower stalks are produced during the second year.

 

Second-year plants can grow to impressive heights topping 8′; however, most mature plants range in size from 4 – 6′.  Leaves are alternate, pinnately compound, branched, and have saw-toothed edges.  Each leaf has 5 -15 ovate to oblong leaflets with variable toothed edges and deep lobes.

 

Mature plants will produce a single, thick, deeply grooved, greenish-yellow stem that sprouts lateral branches topped with hundreds of clusters of the umbellate flowers.  Plants are prolific seed producers meaning that small patches of this weed can develop into large patches in just a few years.

 

Keep in mind that sap in both the first year rosettes and second-year flower stalks contains damaging concentrations of psoralens. Always wear gloves and protective clothing if you find yourself working around any biennial growth stage of this malevolent weed!

 

Mechanical and Chemical Control

The toxic nature of the sap makes mechanical control of wild parsnip problematic.  Hand-pulling is a high-risk endeavor and not recommended.  There have been reports of sap spattered by mowers and string trimmers onto equipment operators producing phytophotodermatitis on exposed arms and legs.

 

The safest approach to controlling this invasive weed is to use herbicides.  Of course, as always, read and follow label directions paying close attention to recommended rates and whether or not surfactants are recommended to enhance herbicide efficacy.

 

Wild parsnip plants are susceptible to postemergent herbicides such as the non-selective systemic herbicide glyphosate (e.g. Roundup) and the contact “burndown” herbicide pelargonic acid (e.g. Scythe).  However, keep in mind that multiple applications of a burndown herbicide may be required to exhaust the energy stored in second-year tap roots.  Effective selective postemergent herbicides include 2, 4-D, clorpyralid (e.g. Transline), and metsulfuron (e.g. Escort XP).

 

 

 

 

Blue Week in Northwest Ohio

Authors Amy Stone

Published on May 15, 2019

 

 

Each May, the partners of the Green Ribbon Initiative assemble a wide array of programs to encourage people to get out into the amazing region in Northwest Ohio and Southeast Michigan. This globally unique region is home to a wide variety of plants and animals such as wild blue lupine, Karner blue butterflies, blue spotted salamanders, big and little bluestem, blueberries, bluebirds, blue racers and much, much more.  We love our blues!

 

The week-long celebration includes everything from bike rides and canoeing, to guided hikes and demonstrations by local experts, the programs offered each year are assembled to encourage people to get out and explore the region and inform them of how diverse and important the region is.

 

Even if you don’t live in NW Ohio, check out the website to learn more and learn why we are happy to be “blue” in the Oak Openings Region! It is a great place to visit and see its uniqueness for yourself.

 

More Information

Oak Openings Blue Week Website

https://www.oakopenings.org/blue-week/

 

 

 

 

Bug Museum Eases Fears

Authors Thomas deHaas

Published on May 14, 2019

 

 

The Lake County Master Gardeners and The Ohio State University Extension presented a Bug Museum for Perry Elementary School on May 8th and 9th, 2019.

 

Classes visited in twenty-minute increments throughout the days. Each class was shown a PowerPoint presentation on the importance of pollinators, and then were free to visit individual stations featuring a collection of bees, beetles and live grubs, cicadas, hornet nests, praying mantis egg sacs, water insects, and much more. Bradley shared, “It’s really weird. I never knew how cool bugs looked up close”. Giada  beamed “I like butterflies the best. They are so colorful. I went to a fair once where they let butterflies go. It was awesome.”

 

Ruby added, “Ladybugs are my favorite”.

“I love how interested the children are in insects! We are grateful to Perry Elementary for allowing us the opportunity to share our collection and teach the importance of native bees and pollinators”, said Amy Goletz, Master Gardener and Bug Day Coordinator. The Master Gardeners are always happy to hear remarks from children like Lucas, a third grader, when he shared, “I found a big bug in my room but I like bugs and didn’t want to kill it. So we caught it and put it outside.” that’s exactly what Amy likes to hear as part a group of over 40 Master Gardener Volunteers in Lake County.

 

Master Gardener Gwen Zeitz amassed the OSU collection over the past 10 years. Along with Gwen, Master Gardener Volunteers Pat Smeby, Jan Downing, and Amy Goletz all answered questions throughout the days.

Answering questions. “That’s what they do as Master Gardeners. They answer questions about all things related to Horticulture”, stated Thomas deHaas, Agriculture and Natural Resource Educator for OSU – Lake County Extension who assisted with the event as well. We offer horticulture help to homeowner every Tuesday from 9-11 AM April through October via Helpline. Residents are welcome to call the helpline at 440-350-2254 or drop into the office located at 99 East Erie Street, Painesville. In addition, we are always looking to welcome more volunteers. We are presently taking application for new intern trainees that will begin in August.

 

If you love bugs, The Lake County Master Gardeners and The Ohio State University Extension will be participating (as they do every year) in “Bug Day!” at Penitentiary Glen on September 8th, 2019. See you there!

 

 

 

Dogs Gone Wild!

Authors Thomas deHaas

Published on May 13, 2019

 

 

Dogwoods are in full bloom in Northeast Ohio. They are beautiful: Whites, Pinks and Pale Pink.

 

However, are you sure that is what you want to install? Consider where dogwood grow in the wild. They are an understory plant on the edges of woods and they like moist, well-drained soil containing organic matter with a slightly acid Ph. So before you run out and buy that beautiful white or pink dogwood, ask yourself, is this the right plant for the right place. Dogwoods that are under stress will deteriorate over time.

 

They can get borers, sunscald and cankers. Most of these will be a greater problem when the tree is grown in full sun and suffers drought in the summer, which can lead to leaf scorch as well. Be kind to some of our favorite dogs (Dogwood).

 

Just consider right plant, right place.

BYGL Weekly News for May 6, 2019

The following articles were compiled during the last 7 days by members of the Extension, Nursery, Landscape, Turf (ENLT) team to benefit those who are managing a commercial nursery, garden center, or landscape business or someone who just wants to keep their yard looking good all summer.  Access the BYGL website for additional information on other seasonal topics at: http://bygl.osu.edu

For more pictures and information, click on the article titles.  To contact the authors, click on their names.

Violets in Lawns a Pro? or Con?

Authors Ashley Kulhanek

Published on May 3, 2019

 

 

For many, the lawn is a sacred place where nary a clover or dandelion dare venture.  For others, lawns are becoming more diverse for the sake of bees, or for the sake of giving up on the battle against weeds.  Dandelions and clover may be the first to pop to mind when considering lawn weeds, but this was the first time I had seen violets in turf.

 

From afar, the untrained eye may assume this purple hue in the lawn is creeping charlie, or dead nettle, both common weeds that carry a purple flower.

 

But upon closer inspection, these were violets!  While I treated this as a pot of gold at the end of a rainbow, one of our turf professors shared that wild violets are actually one of the most notorious lawn weeds and are difficult to manage.

 

Violets (viola sp.) spread by seed and by rhizome.  They come in shades of purple, white, and yellow.   Some are bi-color.

 

Violets attract pollinators and are the primary host plant for the caterpillars of a group of butterflies known as fritillaries.  Violets are also the sole food source for the mining bee Andrena violae a specialist bee that only visits violets.

 

Violets establish well in shady, moist areas where turf is not vigorous and cannot out-compete violets and other weeds.  These areas often pose a challenge for turf establishment and so violets may be a welcome option for ground coverage.  However, once established they can spread forth from that tough site into your desirable lawn areas.

Violets can also be a sign of thinning lawns overall, and can establish where lawns are mowed too short , competing with that lawns’ chances of growing thick and vigorous once more.

 

So what to do!?

 

Of course, the choice is yours!  Should they stay? OR should they go?  Those found at Chadwick seem to have become part of the display and were a welcome sight to frolic through this spring.

 

Should you desire to manage your violets in lawns, there are options.  If a patch is caught early, it may be best to dig and hand pull them for control.  Consider the conditions of the site as well.  Is there the option to increase light penetration or create a thicker stand of turf to compete with weeds?  Chemical control for violets include the use of post-emergent broadleaf herbicides containing the active ingredient Triclopyr.  Two or more applications may be required to make an impact on established violets.  Fall application when plants are directing energy to the roots is considered most effective.  Even with a solid product, control of violets is difficult.  They’re tough little things!  When using pesticides, be sure to read all labels and follow instructions.  The label is the law for use.

 

More Information

Lawn Talk University of Illinois

https://extension.illinois.edu/lawntalk/weeds/managing_creeping_charlie_and_vio…

 

 

 

 

Land of the Bizarre: Tree Moats and Volcano Mulch

Authors Joe Boggs

Published on May 3, 2019

 

 

Sometimes we run across bizarre things in Ohio landscapes that simply defy explanation.  Such was the case yesterday when I came across “tree moats” (sometimes called “mulch moats”) in a park near my home in the southwest part of the state.  I’ve encountered this bizarre practice before and fail to fathom the logic.

 

As their name implies, tree moats are created by excavating a moat-like ring around trees or shrubs at about the dripline, or slightly beyond.  This is done with an edger or a shovel.  In either case, there always appears to be a concerted effort to sever roots growing beyond the excavation zone.

 

If a shovel was used, the excavated turf and soil is often piled over the root zone rather than carting it away.  Of course, this can serve as a great foundation to create truly noteworthy mulch volcanos (more on this later).

 

What’s Wrong with This Picture?

Plants don’t have a cardiovascular system to ship oxygen to the roots.  The root cells acquire oxygen directly from their environment.  Piling soil on top of the root zone blocks oxygen from infiltrating the soil.

 

If the primary root system dies, certain trees have the capacity to form a “secondary” root system (even “tertiary”) from buds located on the main stem.  However, this elevated root system growing into a mound of soil is subject to a number of tree-debilitating issues including moisture stress.  Mounding soil enhances soil drying and the slopes can shed rainwater reducing water infiltration.

 

When roots reach the edge of the mound, they may turn back towards the main stem; the roots can’t grow into thin air despite needing oxygen!  Eventually, these roots encircle the tree trunk and merge with the stem tissue.  As these errant roots increase girth, they gradually girdle the trunk and restrict vascular flow.  Thus, they are known as “stem-girdling roots.”

 

Cutting roots that cross the tree moats may harken back to the days when we thought that tree roots are confined to an area within the dripline.  We also envisioned tree root systems as being mirror images of the canopy with the roots extending deep into the soil.

 

Of course, research has taught us that a tree’s root system actually looks like a giant Frisbee.  Taproots are rarely present because oxygen levels decline with soil depth.  Over 80% of the “feeder roots” are in the upper 6 – 8 in. of the soil; that’s where the highest level of oxygen is found.  The horizontal spread of a tree’s root system is 2.5 – 3.0 times the crown spread with more than 60% of the roots growing outside the dripline.  Obviously, cutting the roots at the dripline is a recipe for a tree health disaster.

 

The Great Cover-Up

Tree moats and so-called “volcano mulch” often go hand-in-hand; perhaps to hide the first offense.  Volcano mulch is so-named because of its sculpted resemblance to a stratovolcano; like Mount St. Helens before it blew its top.

 

Frankly, I fail to understand why in the name of all that is horticulturally holey do we continue to see mulch piled around tree trunks to stratospheric heights?  What is the appeal?  And, why can’t we stamp out these mulch monstrosities despite years of educational efforts?

 

Volcano mulch does not kill trees outright; if it did, people wouldn’t do it.  Instead, it produces many of the same subtle, long-term, ill-effects I’ve described with soil mounded over a tree’s root system during tree moat excavation.

 

Although bark mulch is at first light and airy, it will ultimately compact as it degrades to interfere with oxygen reaching tree root cells.  Trees respond by growing roots into the mulch; however, the roots can become exposed as the mulch further degrades.

 

As with the soil mounded onto the root system during tree moat excavation, volcano mulch can also cause roots to turn back towards the main stem to encircle the tree trunk.  In fact, it is common to see stem-girdling roots associated with volcano mulch, particularly with maples.

 

As the mulch decomposes and dries out, it will eventually start to repel water; it becomes hydrophobic.  You can observe hydrophobicity of dry organic matter when you try to moisten a bag of dry peat moss.  Of course, water repellency ultimately causes infiltrating roots to dehydrate.

 

The deleterious nature of tree moats and volcano mulch are not immediately apparent.  While moisture starvation and vascular strangulation can ultimately kill a tree, along the way they produce tree stress.  This can induce trees to drop their defenses against infestations by opportunistic insect pests such as native borers or infections by plant pathogens.  Of course, the pests and diseases get blamed if a tree succumbs, not the bizarre horticultural practices that set the tree’s demise into motion in the first place.

 

 

 

Calico Scale is Puffing Up: Scale Poo is Raining Down

Authors Joe Boggs

Published on May 2, 2019

 

 

Calico scale (Eulecanium cerasorum) females spend the winter as small, crusty late instar nymphs (crawlers) stuck on plant stems.  Although clearly evident, they may be missed by the uninitiated.

 

Everything changes in the spring when the females “puff-up” as they mature and start pumping out impressive quantities of honeydew.  This is currently happening in southwest Ohio much to the consternation of anyone who parks their cars beneath infested trees.

 

Calico scale is a “soft scale” meaning that female scales are protected by a soft helmet-shaped shell.  This is a relatively large soft scale with mature female shells measuring about 1/4″ in diameter. The scale’s common name comes from the starkly contrasting calico pattern of black-and-white markings on the shells of live females found on the stems in late spring to early summer.

 

Scale Poo Origins

As with all soft scales, calico scale adults and nymphs (crawlers) feed by inserting their piercing-sucking mouthparts into phloem vessels.  They must extract a large amount of sugary sap flowing through the vessels in order to acquire the small amount of amino acids dissolved in the sap that are used to build proteins.

 

They discharge excess sap from their anus in the form of a sticky, sugary, clear liquid called “honeydew;” a polite name for liquid scale poo.  The honeydew drips onto the leaves and stems of infested trees as well as understory plants, sidewalks, lawn furniture, and stationary entomologists.  I visited some infested trees yesterday to check the development of the scale and my hat, shirt, glasses, and camera quickly became speckled with the sticky scale poo goo.

 

Black sooty molds quickly colonize the honeydew imparting a black veneer to stationary objects.  Despite its unsightly appearance, the sooty molds cause no direct harm to plants other than possibly interfering with photosynthesis.

 

What’s Up Next?

Currently, calico scale females in southwest Ohio are only about 1/2 – 3/4ths their mature size.  They will continue to spew honeydew as they mature towards egg production.  The females can produce more than 1,000 eggs, so populations can build rapidly.

 

Calico scale females die after producing their eggs and quickly turn reddish-brown and appear deflated.  The dead females will remain evident throughout the remainder of the season and may give the false impression that control efforts such as insecticide applications were effective.  In fact, I’ve received pictures over the years of calico scale females that died of natural causes but were being used as proof that an insecticide application was effective.

 

The 1st instar crawlers that hatch from the eggs migrate to the underside of leaves where they attach themselves to veins.  They suck fluid from phloem vesicles and drip honeydew; it’s a family business.

 

A Host of Problems

Calico scale has a wide host range.  In fact, few landscape trees in Ohio other than conifers are beyond the reach of this Asian native.  Here is a partial A-to-Z list of possible hosts:  buckeye, crabapple, dogwood, elm, hackberry, hawthorn, honeylocust, magnolia, maple, oak, pear, redbud, serviceberry, sweetgum, tuliptree, poplar, witchhazel, yellowwood, and Zelkova.

 

Fortunately, as with most soft scales, calico scale is seldom a direct killer of established landscape trees.  But heavily infested trees may suffer branch dieback and the accumulated stress caused by substantial sap loss coupled with other stress-producing conditions may kill trees.  So, the best first step in scale management is to resolve other issues that may affect overall tree health.  I’ve frequently observed large, heavily infested honeylocusts that are planted in good sites showing no obvious symptoms.  Of course, I don’t park my car beneath them.

 

Out of Control

Unfortunately, this is one of the most difficult to control scale insects that you may encounter in Ohio landscapes.  I predict this Alert will generate a number of e-mails sent to me about the “sure-fired” efficacy of a wide range of insecticides.  However, for every glowing testimonial about a particular product, I will receive an equal number of e-mails declaring the product doesn’t work.  I do not believe this reflects errors in observations; it reflects inconsistencies in achieving satisfactory outcomes even with the same products.

 

The high variability in insecticide efficacy has even been reflected in the results of trials conducted by university researchers.  Systemic neonicotinoid insecticides that are effective against other soft scales have produced highly variable results against calico scale.  Dinotefuran (e.g. Safari) produced satisfactory results in some university efficacy trials while delivering no control in others such as an OSU trial I was involved with in 2014.  We targeted crawlers attached to the undersides of leaflets in July and failed to achieve acceptable control with dinotefuran as well as an insect growth regulator.  Only Onyx (bifenthrin) provided good results; however, I’ve heard mixed outcomes from arborists using this approach.

 

Cliff Sadof (Purdue Entomology) has been involved with numerous calico scale insecticide efficacy trials over the years and I contacted him a few months ago to seek his perspectives on the varying results.  Based on observations he made with some dinotefuran trials, he posited that there may be a connection between achieving good control and providing adequate and consistent irrigation after the application.  I believe it’s something applicators should strongly consider.

 

Regardless, there are few effective management tactics that can be applied at this time of the year to suppress a calico scale infestation.  Unlike many other soft scales, calico scale is not controlled with horticultural oil applications.  Dormant oil applications are also ineffective.

 

However, in a pesticide applicator training presentation, Dan Potter (University of Kentucky, Entomology) reported that a number of years ago, a UK entomologist armed student volunteers with bathroom scrub brushes to physically remove calico females before they produced eggs.  The method worked well and could be considered for small trees.  Sometimes we forget the value and efficacy of simple, direct methods to control insect pests.

 

 

 

Secrest Spring Sojourn

Authors Jim Chatfield

Published on May 2, 2019

 

 

On Tuesday, despite the misting rain, I felt it would be horticultural malpractice to not get outside for a walk, camera in hand, at OSU’s Secrest Arboretum in Wooster. The plants outside stopped sleeping/the amphibians still are peeping/buds leaves flowers and fruits are here/It’s the greenest time of year. What did I see?

 

First up are Deciduous Conifers. Needles and cones – evergreen, right? Not always. We have four genera of conifers that lose their needles in the fall in Ohio: dawnredwood (Metasequoia), baldcypress (Taxodium), larch (Larix), and goldenlarch (Pseudolarix). Check out the compound names of dawnredwood, baldcypress, and goldenlarch, denoting that these trees are not true versions of redwoods or cypresses or larch, but different plant types, kind of like pineapple is not a pine or apple. Enough. I feel like a comma queen or at least a grammar grand-duke or a punctuation prince!

 

More importantly, these trees are fascinating as their new needles emerge for the year. Come see a twisted stem version of the Japanese larch, the cultivar ‘Diana’, showing just a touch of cold injury but with soft green needles and unusual curvy stems. Cold injury? When could it occur – when was our last frost, anyway – March? What a great spring. Goldenlarch and dawnredwood needles are just emerging and are wonderful against the sky.

 

Next, near the Children’s Garden at Secrest is a Camperdown elm, though the exact relationship to the original contorted sport found at Camperdown House in Dundee, Scotland is obscure, at least to me, though the original Camperdown was apparently grafted onto Ulmus glabra. Like American elm (Ulmus americana), Camperdown elm produces its flowers and fruits in spring, unlike the lovely lacebark elm (Ulmus parvifolia) with its late summer flowers and subsequent fruits.

 

Years ago, in the old Shade Tree Plot at Secrest, a heavy late fall wet snow got caught up on still present lacebark elm fruits and the weight resulted in major branch breakage. As for the lovely low-growing “Camperdown-ish” elm at Secrest, they are in heavy fruit now, and are a light, fresh green delight.

 

Culinary note: I should probably serve these wafer-like fruits in a vinaigrette. I did once partake of an elm -fruit salad in China. Vinegary; about the same flavor as goldenraintree shoots or willow leaves in vinaigrette at a restaurant at the Great Wall. Speaking of fine dining, when I googled Camperdown elm, I noticed there is an Camperdown Elm restaurant in Park Slope, Brooklyn. Since it is a few miles from my daughter’s apartment I shall have to try it out soon. Hmm, let’s check the menu: “Crackers made with squid ink topped with a paté of mackerel.” I’ll bet it goes great with marinated elm fruits!

 

Crabapples. Those who know my crabarian ways now will expect a pome tome, but I shall resist except to say that a number of crabapples have already started to bloom at Secrest, but many are in that most perfect malusarian moment: when buds and their inner blossoms are of different color combination. There is a 2-3 week span from the earliest to the latest crabapples for bloom, so there is no one time for all, but I decree that this weekend and early next week will be the Crablandia Peak. Come scale Secrest.

 

New Leaves. Do not. Do not miss this. There is nothing more wondrous in nature and so easy to miss than the emergence of new leaves and their accoutrements this time of year. Nurserymen and landscapers and garden center professionals and arborists are so busy they have little time to pause for a few moments. The rest of us may not pause in the yards if there is a sprinkle or two. End-of-school activities deflect us. But just do it. Take some time each day to focus your attention and even to make your own weather and note how lovely reawakening life arrives.

 

The tiny miniature leaves of oaks along with their dangling flowers. Hostas swirling and rising from their winter slumber. Ladys-mantle with it hydrophobic leaves pooling crystalline water droplets. The many versions of maples unfurling and often paired with their often not noticed flowers. The otherworldly sticky buds bursting and unraveling into leaves of horsechestnuts and their hybrids.  Check all of this out at Secrest or at a park or landscape or streetscape or backyard or balcony near you.

 

Rhododendrons. A few azaleas are out at Secrest, but the glory of the genus Rhododendron is yet to come. Nevertheless, I share here one rhododendron picture. My office on the second floor of the Old Administration Building at the OARDC in Wooster is the one on the second floor with the air conditioner attached. Visit sometime and I will try to take you to the tower of the building, or at least to the tunnels below. If.  If the rhododendron has not swallowed me up by then: I advise you come before my retirement in the year 2525…If man is still alive…If woman can survive…

 

Flowers. With buds like pearls, as in pearlbush (Exochorda). Butter yellow flowers on a cucumbertree hybrid (magnolia). A panicle of flower buds on red buckeye. Sassafras flowers; here for only a short time. Soft pink Carolina silverbell flowers each subtended by a chocolate-colored calyx (the floral envelope made up of sepals behind the petals). Common lilac flowers bursting from buds right on its growing degree-daytime schedule of 234. River birch catkins (the male flowers) filled with pollen. Headily sweet aromas of fragrant viburnum blooms.

 

Buckeyes. The flowering period for Ohio buckeyes, horsechestnuts, and buckeye-horsechestnut hybrids is past for Secrest, but red buckeyes and later yet, bottlebrush buckeyes are yet to flower. Nevertheless, the flower buds of red buckeye and the wonderfully creased leaves just emerging on both of these buckeyes are outstanding now.

 

A Final Disease (or Three). Cedar rusts. Joe Boggs did a more complete job with wondrous images in a recent bygl-alert (Rusts Arise :node 1244), but there can never be enough pathological parsings. Cedar rust diseases are a fascinating example of plant host range. To complete its life cycle and the plant disease cycle, the fungus must go through an elaborate ballet of spore stages while spreading from junipers (Eastern red cedars) to a rosaceous host, such as apple/crabapple, hawthorn, quince and serviceberry, among other members of the rose family. Right now the dance consists of microscopic spores emerging enmasse from spectacular abnormal growths (galls) on the juniper, blowing in the wind, randomly answering the call of a windward rose family host.

Lacking Marvelesque microscope-eyes, we will not see their arrival on the hawthorn et al, their infection thereupon, or their conjugal visits with each other, but will see them again when a new spore mass emerges on the underside of the leaves and on fruits. For now, though, what we see is the orange spore horns emerging on the junipers. Risking a pie in the face from an apple orchardist, I will say, the orange telial horns emerging from the galls on junipers now is as pretty as a (admittedly) garish flower.

 

My final, and I have heard for years by professional landscapers and home gardeners alike – controversial – flower pick right now is –sweetgum, Liquidambar styraciflua. Oh, the wonders you’ll see, if only you look.  Right there along with the much-maligned mace-like gumballiferous fruits from the past season, are the cool tiny gumball female flowers and the male cone-like pollen-bearing flowers nearby. Exquisite, even if you hate later cleaning up the eventually brownish, spiky, fruits unpleasant for landscaper equipment and barefoot gardener feet.

 

All this – and much more on a short Spring Sojourn Walk at Secrest.

 

 

 

 

SADD Garden brings Happiness!

Authors Thomas deHaas

Published on May 2, 2019

 

 

Students at Perry High School in the group, Students Against Destructive Decisions (SADD) installed the Good Decision Garden at the entrance of the school.

 

Students walk past the planting as they arrive and leave school each day, enjoying the flowering display all spring.

With donations from local nurseries, the students installed materials last fall with the goal of continuous color from March through July, under the guidance and direction of OSU Extension-Lake County. Students are excited to see what will bloom next.

 

Plant Suggestions for the Good Decisions Garden (Flowers April-June)

Early Spring:

  • Dicentra – Bleeding Heart
  • Creeping Phlox

Bulbs:

  • Hyacinth
  • Daffodils
  • Tulips

Late Spring:

  • Allium (purple sensation)
  • Lilac ‘Miss Kim’
  • Peony pink dawn
  • Weigela

Early Summer

  • Astilbe
  • Huceralla

Not only is the garden making a difference in student lives, it made a difference in those who installed the planting.

 

 

 

A Bright Spot with Spotted Lanternfly

Authors Joe Boggs

Published on May 1, 2019

 

 

It may be wise to be skeptical when hearing news that a native bio-ally is coming to our rescue in dealing with a non-native insect pest.  Disappointments abound.  Non-native juggernauts may steamroll because our native predators, parasitoids, and pathogens (the 3-Ps) just don’t recognize them as a food source.

 

Of course, sometimes they eventually do.  Good examples are Japanese beetles (Popillia japonica) and gypsy moth (Lymantria dispar).  In many parts of the U.S., these non-natives now behave much like natives with periodical outbreaks eventually crashing because of the 3-Ps as well as environmental challenges.

 

That’s why cautious optimism may be justified with recent news about a discovery near Reading, PA, of two native fungal insect pathogens hammering spotted lanternfly (SLF) (Lycorma delicatula).  The two unrelated native fungi were Batkoa major and Beauveria bassiana and they produced two different diseases that significantly reduced the SLF population.

 

The research was published on April 22, 2019, in PNAS:  Proceedings of the National Academy of Sciences of the U.S.A.  Quoting from the research paper:  “This coepizootic occurred when females were gravid but before most oviposition, and due to the massive L. delicatula mortality, only 12 egg masses were found.”

 

You can read the entire paper by clicking this hotlink:  https://www.pnas.org/content/early/2019/04/24/1903579116

 

You can also read a nice summary with quotes and informative perspectives from two of the paper’s authors, Eric Clifton and Ann Hajek, by clicking this hotlink:

https://www.sciencedaily.com/releases/2019/04/190430164244.htm

 

 

 

 

Be Alert for Pine Needle Scale Crawlers

Authors Joe Boggs

Published on May 1, 2019

 

 

Our native Pine Needle Scale (Chionaspis pinifoliae) was once a common and troubling “key pest” back when Mugo pines (Pinus mugo) rivaled yews (Taxus spp.) and junipers (Juniperus spp.) as one of the most common landscape plants in Ohio and Scotch pine (Pinus sylvestris) was THE Christmas tree grown in our plantations.  However, that’s changed over the years.

 

As mugos have become less common in our landscapes and Scotch pines largely replaced by other conifers in our Christmas tree plantations, so has the occurrence of pine needle scale become a rare thing in both locations.  In fact, I’m now down to only one landscape in southwest Ohio where I can monitor a scale-infested mugo.  All of the other locations have removed their mugo “scale trees.”

 

However, that doesn’t mean we should turn our backs on pine needle scale; plant pests have a way of sneaking up on us when we do.  Beyond Scotch and mugo pines, this native scale may be found on a wide range of conifers including eastern white pine (P. strobus); Douglas-fir (Pseudotsuga menziensii); hemlocks (Tsuga spp.); spruces (Picea spp.); junipers (Juniperus spp.); cedars (Cedrus spp.); and firs (Abies spp.).

 

Armor Up!

Pine needles scale is a type of “armored scale” (family Diaspididae) meaning much of its life-cycle is spent under a hard protective covering.  Armored scales insert their long piercing-sucking mouthparts into plant tissue to slurp-up the contents of ruptured plant cells.

 

This is unlike so-called “soft scales” (family Coccidae) that feed by inserting their piercing-sucking mouthparts into phloem vessels to extract amino acids that are dissolved in the sugary plant sap flowing through the vessels.  They discharge excess sap from their anus in the form of a sticky, sugary, clear liquid called “honeydew;” a polite name for scale diarrhea.  Of course, the honeydew is commonly colonized by unsightly black sooty molds.  Armored scales do not produce honeydew, so infested trees do not become blackened with sooty mold.

 

As with all armored scales, pine needles scale 1st instar nymphs are the only mobile stage in this sucking insect’s life-cycle; thus, the name “crawler.”  It is also the stage that is most susceptible to insecticide applications.  The tiny, dot-like pine needle scale crawlers are dark pinkish-red to rusty-red.  Once the crawlers settle to feed, they turn tannish brown.  A 10x hand lens is helpful with detecting and monitoring the scale crawlers.

 

It’s a Generational Thing

Overwintered pine needle scale eggs are hatching right now in southern Ohio.  This scale has two generations per season with populations expanding considerably with the second generation; the so-called “summer generation.”  This means reducing the number of first-generation crawlers (the “spring generation”) will have a significant impact on decreasing the overall infestation by preventing the population contribution by the second generation.

 

Also, first generation eggs typically hatch over a relatively short period of time meaning that if management includes the use of a topical insecticide, a single application may be sufficient.  Second generation eggs hatch over a prolonged period of time often requiring multiple applications depending on the residual activity of the insecticide product.

 

Spring generation crawlers hatch from overwintered eggs when the accumulated Growing Degree Days (GDDs) reach 305.  Although common lilac (Syringa vulgaris) reaches full bloom at around 315 GDDs, I’ve found this to be a pretty good indicator plant for the appearance of 1st generation crawlers.

 

Research has shown that a number of bio-allies such as lady beetles and other scale predators as well as parasitoids play an important role in holding scale populations below damaging thresholds.  Insecticidal soaps and horticultural oils are effective against scale crawlers and will spare the beneficial insects.  The downside is that both will only kill on contact meaning that thorough coverage is required since there is no residual activity.  This also means pine needle scale crawlers should be closely monitored in case an extended egg hatch occurs and new crawlers escape the first application

 

Many standard insecticides labeled to control armored scales on the infested conifer species are also effective against scale crawlers.  However, the downside is that these products may also kill bio-allies.

 

The systemic neonicotinoid, dinotefuran (e.g. Safari, Transtect, Zylam, etc.), has proven effective against armored scales and will have a limited impact on beneficials.  However, applications must be made prior to egg hatch to allow time for the active ingredient to reach plant tissue in concentrations sufficient to kill the crawlers.  The neonicotinoid, imidacloprid (e.g. Merit), is not effective against armored scales.  In fact, some research studies have shown applications of this systemic insecticide actually contributes to scale outbreaks.

 

 

 

 

Helicopters Fly over Lake County in May!

Authors Thomas deHaas

Published on May 1, 2019

 

 

Lake County is one of 51 counties in Ohio that fall under the European Gypsy Moth Quarantine.

 

Currently 51 counties in Ohio are regulated under the Gypsy Moth quarantine. Gypsy Moth regulated articles include, but are not limited to: trees and woody shrubs, including cut Christmas trees; logs, pulpwood, slab-wood, firewood, and wood-bark chips outdoor household articles, including: tables, doghouses, planters, garden equipment, playhouses recreational vehicles other products or articles, or means of conveyance that may carry a life stage of the Gypsy Moth

 

Producers who ship nursery stock out of regulated areas to non-regulated areas must have their stock inspected and a certificate, which attests to the fact that their product is free of gypsy moth, must accompany each load.  Producers, who make repeated shipments, are urged to take steps necessary to qualify for a “Gypsy Moth Compliance Agreement” and master certificate; otherwise, they will face delays in obtaining certificates.

Compliance Agreements are written agreements between an entity engaged in growing, selling, processing, or moving regulated articles from a regulated area and the Ohio Department of Agriculture, setting forth specified conditions to prevent the spread of the gypsy moth. This agreement is needed by anyone moving regulated articles out of a regulated area to a non-regulated area and anyone in a non-regulated area receiving regulated articles from a regulated area.

One main requirement for the compliance agreement is that nurseries must apply a USDA-approved insecticide to the entire growing area in mid to late May.

 

For more information, contact the Plant Pest Control Section at 614-728-6400 or your local nursery inspector.

https://agri.ohio.gov/wps/portal/gov/oda/divisions/plant-health/gypsy-moth-program/

Assume that helicopters will be spraying in late May 2019. Typically, the product sprayed is a growth regulator that prohibits the European Gypsy Moth to complete its life cycle into an adult moth that is able to reproduce. The product used has a low toxicity to people and pets. People are encourage to stay indoors while active spraying is occurring. If you have any other questions, please feel free to contact the Ohio State University Office of Extension – Lake County, Ohio.

 

Thomas deHaas – Agriculture Natural Resource Educator

dehaas.2@osu.edu 440-350-2269

 

 

 

 

Cold Case Cracked: Crime on Crabapple Exposed?

Authors Jim Chatfield

Published on April 30, 2019

 

 

One of the intemperate dilemmas for plants in the off-season is stem damage known as “frost cracks”.  It is not completely understood, but one working theory is that with rapid temperature fluctuations, water in stem cells moves out of the cells during warm weather, freezes, and damages the shrunken stem cells. Longitudinal cracks in the trunks then develop.

 

Precisely what conditions result in frost cracks on a particular plant and did we see a lot of this resulting from the winter of 2018-2019? This is difficult to answer since sometimes damage to the stem is not apparent until later in the growing season, but we have not heard of widespread damage this spring. Did rapid temperature plunges occur on certain days this winter or early spring – hard to say depending upon the particular plant microclimate. However, herein is one seemingly clear-cut case of crabapple crime.

 

One clue is that the northeast Ohio ‘Sentinel’ crabapple in question is thin- and smooth-barked when young and crabapples and apples (the genus Malus) are one of the trees, along with maple, beech, lindens and others that are particularly susceptible to frost cracks when young. Second, damage from frost crack is typically worst on the southern or southwest exposures of the stems, and that was the case for the each of the trees in this incident.

 

What is the prognosis for these trees? Damage may cause problems, primarily by exposing the stems to ingress by pests and pathogens. However, frost cracks are not necessarily harbingers of doom. Otherwise healthy trees often develop good callus at the edge of the cracks and proceed into their teens and on to older age. Time will tell. Clean up the crispy bark along the edges and employ typical plant health maintenance.

 

What can be done to prevent frost cracks in the first place? The most typical approach is the use of tree guards or white latex paints on the trunks of young trees of susceptible species. The idea for this is to protect the tree from overheating during the heat of a winter or early spring day in which rapid temperature plunges then occur. This is why orchardists paint the trunks of fruit trees in order to reflect the heat of the sun during the warm period of the day.

 

These measure are less commonly seen with crabapples then apples, but it is a good idea. “Sentinel” means “to guard, to stand and keep watch.” Apparently, this ‘Sentinel’ crabapple, this member of the “Night Watch”. failed in its vigil at this place in this time.

 

 

 

 

It’s the Most WONDERFUL Time of the Year…………… If you’re a Gardener

Authors Thomas deHaas

Published on April 29, 2019

 

 

It all happened at once this year. Forsythias, Magnolias, Dogwoods, Serviceberry are all blooming near the same time. In addition, Crabapples, Quince, Cherry, Pieris, Phlox, Hyacinth, and Tulips are all in flower. Although invasive, even Flowering Pears are pretty as well.

 

PJM Rhododendrons are striking.

 

It was a wonderful spring for Magnolias with no hard frost through the flowering season.

 

As you admire the beauty of all in flower, make a note of what you would like to add or replace in your landscape.

Enjoy the “Most Wonderful Time of the Year”!

 

BYGL Weekly News for April 29, 2019

The following articles were compiled during the last 7 days by members of the Extension, Nursery, Landscape, Turf (ENLT) team to benefit those who are managing a commercial nursery, garden center, or landscape business or someone who just wants to keep their yard looking good all summer.  Access the BYGL website for additional information on other seasonal topics at: http://bygl.osu.edu

For more pictures and information, click on the article titles.  To contact the authors, click on their names.

Rusts Arise!

Colorful displays of three types of rust fungi are appearing on junipers in Ohio. The fungi belong to the genus Gymnosporangium and they complete part of their life-cycle on members of the plant genus Juniperus and the other part of their life-cycle on members of the family Rosaceae. In biological terms, this type of life-cycle is known as “heteroecious.”
Published on
Authors
Joe Boggs

Red Bark on Sycamore and London Planetrees

Red Bark Phenomenon
Last Wednesday, Jerry Frankenhoff (Urban Forester, Great Parks of Hamilton County) sent an e-mail message asking about red staining on the bark of sycamore trees. He wrote that he’d never seen anything like this before. I was shocked when I looked at his attached image. Likewise, I had never before seen the unusual reddening symptoms on sycamore or any other tree.
Published on
Authors
Joe Boggs

Growing Degree Days (GDD) in Ohio

Growing Degree Day (GDD) Website
Each Tuesday, members of the Extension Nursery Landscape and Turf (ENLT) have a virtual meeting to discuss what they are seeing in their own area and talk about those “stumpers” that they have come across in the horticulture world and get feed back from others in the group.
Published on
Authors
Amy Stone

Imperial Fritillary

Imperial Fritillary in Bloom
The imperial fritillary or crown imperial (Fritillary imperialis) is blooming in gardens in northwest Ohio now. The plant comes in various shades of yellows, oranges and reds. The pendulous flowers are about 2″ long and are found clustered at the terminal end of stout and leafless stem that towers above the leaves below. Above the flowers are a sheaf of smaller leaves that form a tuft of green as shown in the photo below.
Published on
Authors
Amy Stone

BYGL Weekly News for April 15, 2019

The following articles were compiled during the last 7 days by members of the Extension, Nursery, Landscape, Turf (ENLT) team to benefit those who are managing a commercial nursery, garden center, or landscape business or someone who just wants to keep their yard looking good all summer.  Access the BYGL website for additional information on other seasonal topics at: http://bygl.osu.edu

 

For more pictures and information, click on the article titles.  To contact the authors, click on their names.

 

 

Be Alert for Boxwood Leafminer

Authors Joe Boggs

Published on April 12, 2019

 

 

Boxwoods with yellow to brown leaves are common this spring throughout Ohio.  Boxwoods with yellow to brown leaves are common this spring throughout Ohio.  Some of the leaf discoloration is due to winter injury with foliage at the tips of branches or on the windward side of plants most heavily affected.

 

Some discoloration was caused by salt damage either directly with “ice melt” or rock salt inadvertently thrown onto foliage, or indirectly with “salt spray” carried onto foliage from nearby roadways.  Salt damage is sometimes, but not always, concentrated on one side of the plant.

 

However, a close examination may also reveal the telltale blister-like leaf symptoms caused by the boxwood leafminer (Monarthropalpus flavus).  Leafmines may be found throughout the plants although the highest concentration often occurs on foliage at branch tips.

 

Gently separating the upper and lower leaf surfaces (the leafminer had already done most of the work!) will reveal the bright yellow leafmining larvae (maggots) of this midge fly wiggling around in their blister mines.  The larvae will complete their development in a few weeks and pupate.  The pupae are also bright yellow at first, but turn orangish-yellow as this stage nears completion.

 

This non-native midge fly was accidentally introduced into North America from Europe in the early 1900s and is now common throughout Ohio.  Adults emerge at around the same time red horsechestnuts (Aesculus × carnea) and doublefile viburnums (Viburnum plicatum) are in full bloom (440 GDD).  Except for their bright orange abdomens, the adults superficially resemble miniature mosquitoes.

 

Females use their needle-like ovipositors to insert eggs between the upper and lower leaf surfaces of boxwood leaves.  Each leaf may contain multiple oviposition sites with several eggs per site.  These sites will become individual leafmines producing the blister-like leaf symptoms.

 

Eggs hatch in early-summer and the resulting larvae spend the remainder of the season consume interior leaf tissue as they develop through the 1st and 2nd instar stages.  Winter is spent as 3rd instar larvae inside the leafmines.  The larvae resume feeding in the spring and develop through a 4th instar stage.

 

Much of the leaf damage occurs in early spring with the ravenous larvae rapidly expanding their leafmines.  Multiple leafmines in individual leaves may coalesce causing the upper and lower leaf surfaces to delaminate over the entire leaf.  Individual mines may turn reddish-green at this time of the year with heavily mined leaves turning from yellow to orangish-brown causing the leafmining damage to be mistaken for winter injury.

 

A close examination of the leafmines at this time of the year may reveal small translucent “windowpanes” created by the larvae in the lower leaf surface.  The pupae will wiggle through these weak points to ease the emergence of fragile adults.

 

This pupal activity is responsible for one of the most unusual features of this midge fly:  reports of hissing, crackling, or rustling sounds coming from heavily infested boxwoods.  I’ve reported on this strange phenomenon in past BYGLs.  So, reports from gardeners or landscapers that they’ve heard boxwoods going snap, crackle, and pop should be taken seriously as the odd sounds are an indicator of a heavy boxwood leafminer infestation.

 

Damaging boxwood leafminer infestations can be suppressed through applications of neonicotinoids such as imidacloprid (e.g. Merit, Marathon, and generics) or dinotefuran (e.g. Safari or Zylam).  However, applications should be delayed until AFTER boxwoods bloom to protect pollinators.

 

Boxwood blooms attract a wide range of pollinators; blooming plants can literally buzz with their activity.  Delaying applications until blooms drop will result in some minor miner damage, particularly with the imidacloprid that is taken-up more slowly compared to dinotefuran.  However, this is a small price to pay for protecting pollinators.

 

You may find recommendations for topical applications of pyrethroid insecticides such as bifenthrin (e.g. Talstar) to target adult leafminer females before they lay eggs.  However, adults typically emerge in Greater Cincinnati while boxwoods are in full bloom, so I no longer recommend this application.

 

Plant selection provides a more long term solution to the depredations of boxwood leafminer by removing insecticides from the management equation.  A helpful research-based listing of the relative susceptibility of boxwoods to the leafminer was published in 2014 by the American Boxwood Society in their “The Boxwood Bulletin” [see More Information below].

 

More Information

American Boxwood Society, Boxwood Leafminer Evaluation

http://www.boxwoodsociety.org/uploads/54_1_2014_Summer.pdf#page=9

 

 

 

How To Hire An Arborist

Authors Amy Stone

Published on April 12, 2019

 

 

Ohio State University Extension’s Home Yard and Garden FactSheet HYG-1032 has been update and is available online. The OSU FactSheet includes tips for selecting an arborist and resources available to help find local arborists.

 

An arborist, by definition, is an individual trained in the art and science of planting, caring for, and maintaining individual trees. Arborists are knowledgeable about the needs of trees and are trained and equipped to provide proper tree care. Hiring an arborist is a decision that should not be taken lightly. Proper tree care is an investment that can lead to substantial returns. Well-cared-for trees are attractive and can add considerable value to your property. Poorly maintained trees can be a significant liability. Pruning or removing trees, especially large trees, can be dangerous work. Tree work should be done only by those trained and equipped to work safely in trees (ISA, 2018).

 

A huge thank you to Cindy Meyer with Warren County Soil and Water Conservation District for her work as a co-author and the photo used in this alert.

 

More Information

OSU Extension Home Yard and Garden 1032

https://ohioline.osu.edu/factsheet/hyg-1032

 

 

 

Green Tigers Prowling Forest Trails

Authors Joe Boggs

Published on April 10, 2019

 

 

I spotted one of my favorite forest dwellers during a walk in the woods yesterday:  six-spotted tiger beetles (Cicindela sexguttata).  The beetles have a curious affinity for hanging out on woodland trails and they can certainly liven up a hike.

 

The beetles are well-named because these tiny “tigers” hunt, kill, and eat other insects.  The overall color of these shiny beetles varies from deep emerald green to slightly bluish-green depending on the angle of the light.  Six white spots are arranged along the trailing edge of the wing covers, three spots per side.  The spots are small and sometimes obscured by light bouncing off their highly reflective shiny bodies.

 

The beetles have bulging black eyes (the better to see you with, my dear!) that makes them look like they’re wearing goggles.  The beetles are agile flyers and their excellent eyesight coupled with long legs which gives them swift speed can make getting a close look difficult.

 

However, a close examination of this ferocious predator will reveal powerful sickle-shaped mandibles that are used to grab and dispatch luckless arthropod prey; a trait that is shared with other tiger beetles (family Carabidae (Ground Beetles); subfamily Cicindelinae (Tiger Beetles)).  A word of caution:  these carnivores can also use their impressive mandibles to deliver a painful bite to the hand of the overly curious.

 

Even the larvae of this tiny tiger are predators.  However, instead of actively hunting their prey, they conceal themselves in vertical burrows in the soil to await hapless victims.  When a meat item such as insects or spiders walks past, the tiger larva springs forth like a jack-in-the-box to grab dinner with their powerful mandibles.

 

The bottom line is that six-spotted tiger beetles are highly effective and important predators throughout their life cycle.  So, keep your eyes peeled for and hands away from these tiny tigers prowling our woodland trails … and don’t kill them since they are good guys!

 

 

 

Magnificent Magnolias

Authors Thomas deHaas

Published on April 9, 2019

 

 

Magnolias come in a range of flower colors and sizes.

 

The two most common in the landscape are Star Magnolia Magnolia stellata, which has a white flower, and Saucer Magnolia Magnolia soulangiana, which has a pale purple flower.

 

Many more cultivated varieties exist which include a yellow, Butterflies Magnolia Magnolia x. ‘Butterflies”, Magnolia x. loebneri ‘Leonard Messel’,

 

Magnolias can grow as a single stem tree form, which can reach 30 feet, or a small specimen tree that can be kept at 10 feet through pruning. Magnolias also come in a multi-stemmed small tree or shrub form.

 

The magnolias as a group are free from cultural problems except for an occasional outbreak of magnolia scale.

 

The one drawback as a group is because they flower so early; they can occasionally be burned by a frost, which will damage the flowers. But the solution is look to the ‘girl’ hybrids which bloom later:

 

By using varieties that bloom later, they tend be less susceptible to frost damage.

Take a look……………Magnolias are ‘MAGNIFICENT’

 

 

 

OHIO STATE UNIVERSITY EXTENSION

 

Where trade names are used, no discrimination is intended and no endorsement by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.

Ohio State University Extension embraces human diversity and is committed to ensuring that all research and related educational programs are available to clientele on a nondiscriminatory basis without regard to race, color, religion, sex, age, national origin, sexual orientation, gender identity or expression, disability, or veteran status. This statement is in accordance with United States Civil Rights Laws and the USDA.

CFAES provides research and related educational programs to clientele on a nondiscriminatory basis. For more information: [ http://go.osu.edu/cfaesdiversity ].

Any materials in this newsletter may be reproduced for educational purposes providing the source is credited.

 

BYGL Weekly News for April 1, 2019

The following articles were compiled during the last 7 days by members of the Extension, Nursery, Landscape, Turf (ENLT) team to benefit those who are managing a commercial nursery, garden center, or landscape business or someone who just wants to keep their yard looking good all summer.  Access the BYGL website for additional information on other seasonal topics at: http://bygl.osu.edu

For more pictures and information, click on the article titles.  To contact the authors, click on their names.

 

Name That Insect . . .

Authors Amy Stone

Published on March 27, 2019

 

 

As temperatures warm, people are outside enjoying the almost, spring-like weather. There are still a few waiting for even warmer temperatures to arrive and stick around for more than a day – you know who you are. As everyone migrates outdoors as temperatures rise, the chances of an insect encounter will be pretty high. At the first encounter, many people may have an urge to “eliminate” the six legged species. Some may have thoughts of a quick step and smush, others may want to reach for a bottle to abolish the “pest.” It is important to take a step back – not necessarily to avoid the insect, but to identify it first and then act accordingly. Many times the recommended action will be to do nothing at all. Many insects that we encounter are beneficial and have important jobs to accomplish in what is typically a rather short life-span. Jobs that would be hindered if we stop their existence simply because we don’t like insects, we have a fear of insects, or just don’t care.

 

Earlier this week, a homeowner had an insect encounter as they were walking around the outside of their home. Instead of going into kill-mode, this homeowner collected the insect and brought it to their local Extension office for identification. Photos were taken of this rather larger black insect and the images began making the rounds being shared among Extension professionals. The insect was identified as the big-headed ground beetle, aka the pedunculate ground beetle (Scarites subterraneus). This insect is a predator and great for the garden.

 

This alert really serves three purposes that we would like to share with the readers:

 

If you weren’t familiar with the big-headed ground beetle, you are now. These ground beetles are very common in cultivated soils. They are about 1/2 to 3/4 of an inch in length, have a flattened appearance, and have front legs designed for digging.

 

Photo Credit: Amy Stone, OSU Extension – Lucas County; Good Garden Bugs by Author Mary Gardiner

 

If you come across an insect that you aren’t familiar with, don’t assume the worst, although there are some bad insects in the bunch. With care, collect the insect or take photos of the insect and do some research. Photos should be clear and also illustrate a size comparison whenever possible. Bad photos can lead to a bad identification or no identification at all. Blurry images can often make it impossible to identification an insect with 100% certainty. Engage your local Extension office, reach out to members of our BYGL writing team, connect with a green industry professional such as a certified arborist, landscaper or garden center expert, or take a look in books or on the internet.

 

And finally, we mention the internet. Just a reminder that not everything you read on the internet is true. While seeking information, you will also have to search out the truth and sort through lots of other information. Sites that end in “edu” are a great place to start.

 

Enjoy the warmer temperatures and expect an insect encounter while you are gardening, landscaping or just enjoying nature this spring.

 

More Information

BugGuide

https://bugguide.net/node/view/2992

 

 

 

 

Learn More About Ash Hazards

Authors Amy Stone

Published on March 27, 2019

 

 

Earlier this month, Joe Boggs authored a BYGL Alert entitled, Ash Breakage: the Hazard Continues (March 19, 2019). To follow-up with this topic, we wanted to alert you to an upcoming webinar from EAB University called Dead Ash Dangers and Considerations for Risk and Removal.

 

The online presentation will be held on April 2, 2019 at 11:00 am (EST).

 

To register click on this link: https://msu.zoom.us/webinar/register/WN_QlthhbABToCfA3b36EHUWA

 

All EABU webinars are free and tuning into many of the live webinars can earn you continuing education credits. If you can’t watch it live, but are still interested in the topic – no problem! All webinars are recorded and posted online after the session. Check out the list of previously recorded sessions on the regionally EAB website at: http://www.emeraldashborer.info/

 

There will be one more live EABU spring session following the April 2 program. On April 16, 2019 at 11 am (EST), Nate Siegert with the US Forest Service will be talking about Emerald Ash Borer: Perspective from a Recently Infested State.

 

While EAB is what some called old news in Ohio, there are folks who want to stay updated on its progress. The EAB invasion has advanced across the Northeast over the last decade, with the first detections occurring in western New York in 2009 and the most recent detections in Maine in 2018. Presently, infestation across the region may be characterized as mix of generally infested areas, newly infested locations, and expanding satellite infestations, with many areas yet to be invaded. The spatial and temporal dynamics of the EAB invasion along the leading edge from New York to Maine will be discussed, including a review of selected management activities, updates on recent changes, and future direction of management and regulatory work in light of reduced funding and potential federal deregulation.

 

Stay updated on EAB and other invasive species through EABU!

 

More Information

Emerald Ash Borer University

http://www.emeraldashborer.info/eabu.php

Regional Emerald Ash Borer Website

http://www.emeraldashborer.info/

 

 

 

The Yellow of Winter Aconite Warms Gardeners Heart – Even Though the Temperatures Remain Cold

Authors Amy Stone

Published on March 27, 2019

 

 

Gardeners are always looking for signs of spring. Although the calendar tells us it is officially spring, Mother-Nature can sometimes send mixed messages.

 

The brightly colored yellow flowers of the winter aconite (Eranthis hyemalis) covering the ground might be just the sign that spring has arrived – at least we hope. Winter aconites are a bulb that will naturalize, creating a blanket of yellow flowers for all to enjoy. In fact, the bees were busy visiting one flower after another while I was out enjoying a walk around the Toledo Botanical Garden.

 

Photo Credit: Amy Stone, OSU Extension – Lucas County

 

The winter aconite is in the family Ranunculaceae. The plant prefers full sun to partial shade. One of my favorite sites to enjoy a naturalized stand is in a woodland garden that later this year will be dominated by shade produced by the mature trees, but in late winter and early spring it is just the perfect setting for these bulbs to show their horticultural-stuff.

 

It is also thought that the winter aconites can be grown among black walnut trees and that deer don’t particularly care for them. I have even enjoyed them peaking up through a blanket of snow. Thank goodness that wasn’t the case when I captured the images earlier this week.

 

If you are establishing this plant in the landscape, you will want to plant tubers 2-3″ deep and 3″ apart in late summer to early fall. It is recommended that you soak tubers overnight before planting. Once established, you may notice some self-seeding and naturalizing over time in optimum growing conditions. They tend not to like being disturbed or moved frequently. It is best to identify the location and let them live out their lives in that spot.

 

The plant is native to Europe. The genus (Eranthis) comes from the Greek words er meaning spring and anthos meaning a flower for its very early flowering. The specific epithet (hyemalis) means of winter or winter blooming.

 

Winter aconites can make a great addition to the front of perennial or shrub borders, in among the rocks in a rock garden, alongside pathways or walkways, and will also do well in containers. They are eye catching in masses and large numbers. Just remember that because they bloom so early in the season, don’t tuck them away in a far corner of the garden, but rather plant them somewhere they can be appreciated and enjoyed even if it is cold outside.

More Information

Missouri Botanical Garden, Plant FInder

http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kemp…

 

 

 

 

 

Be Alert to Poison Hemlock

Authors Joe Boggs

Published on March 26, 2019

 

 

Poison hemlock (Conium maculatum) is a non-native biennial weed that spends its first year as a low-growing basal rosette; the stage that is currently very apparent.  During its second year, plants produce erect, towering stalks and multi-branched stems topped with umbrella-like flowers.  Mature plants can measure 6-10′ tall and are prolific seed producers.

 

Despite its common name, poison hemlock is not a tree; it is a member of the carrot family, Apiaceae (formerly Umbelliferae).  It shares floral characteristics with other non-native members of the carrot family such as Queen Anne’s lace (Daucus carota) and the wild parsnip (Pastinaca sativa) which is notorious for producing sap that causes skin blisters.

 

All stages of the poison hemlock plant have bluish-green leaves that are 3-4 times pinnately compound.  The deeply cut parsley-like leaflets have sharp points.  Flowering plants have hairless, light-green to bluish-green stems that are covered with obvious purplish blotches.  Clusters of tiny white flowers are borne on structures called umbels that look like upside-down umbrellas.

 

Poison hemlock is one of the deadliest plants in North America.  This invasive plant was imported as an ornamental in the late 1800s from Europe, West Asia, and North Africa.  The plant contains highly toxic piperidine alkaloid compounds, including coniine and gamma-coniceine, which cause respiratory failure and death in mammals.

 

The toxins must be ingested or enter through the eyes or nasal passages to induce poisoning; they do not cause skin rashes or blistering.  Regardless, this plant should not be handled because sap on the skin can be rubbed into the eyes or accidentally ingested while handling food.

 

The roots are more toxic than the leaves and stems; however, all parts of the plant including the seeds should be considered dangerous.  Unfortunately, this dangerously toxic plant is becoming more common throughout Ohio including growth in landscape plantings where the close proximity to people increases poisoning risks.

 

While poison hemlock can be partially managed by mowing and tilling, the most effective control approach involves properly timed applications of selective or non-selective post-emergent herbicides including glyphosate (e.g. Roundup).  Each plant produces hundreds of seeds, so applications of herbicides made now will control both the first season rosette stage and the second season flowering stage before seeds are produced.

 

 

 

 

Be Alert for White Pine Weevil

Authors Joe Boggs

Published on March 26, 2019

 

 

White Pine Weevil (Pissodes strobi) females spend the winter out of sight cooling their six heels in the duff beneath their pine or spruce targets.  As temperatures warm in the spring, they climb their hosts to feed and lay eggs in the terminals.  Sap oozing from small holes in the terminals is a calling card of this weevil.

 

Females begin to emerge from their winter abodes when the accumulated Growing Degree Days (GDD) reach 84.  This roughly coincides with the full bloom of northern lights forsythia (Forsythia x intermedia), speckled alder (Alnus incana), and cornelian cherry dogwood (Cornus mas).  We have not yet reached the magic GDD number of 84 in southern Ohio; however, cornelian cherry dogwood bloom buds are beginning to show color meaning the weevils may soon be stirring.

 

This native weevil has a wide conifer host range that includes Scotch, jack, red, pitch, and eastern white pines as well as Douglas-fir and all spruces.  Indeed, the weevil’s love of spruce is exemplified by its alternate common name, Engelmann Spruce Weevil, or simply Spruce Weevil.  White pine weevil is not just found in Ohio; it ranges from the east coast west into the Rockies.

 

The females use their chewing mouthparts located at the tip of their long snout (rostrum) to chew small holes through the bark to feed on the sugar and nutrient-rich phloem.  Eventually, they will turn around and deposit an egg in some of these holes.

 

The resulting white, legless, slightly curved, grub-like larvae tunnel downward side-by-side just beneath the bark feeding on the phloem.  Pupation later this season is marked by the construction of so-called “chip cocoons” by the larvae prior to entering the pupal stage.

 

Infested leaders wilt, turn brown, and die.  Dead leaders occurring in mid-summer which sometimes have a curved “shepherd’s crook” appearance is another calling card of this weevil.  New adults emerge from the infested terminals late in the season to feed and mate.  Females of this second generation then crawl to the duff to spend the winter in preparation for sneaking up on us next spring.

 

The weevils are capable of killing small trees less than 3′ in height, but it does not kill large trees.  However, years of successive damage to terminal leaders will eventually create “cabbage trees” which are short, squat trees with multiple terminal leaders in landscapes and woodlots.  Of course, loss of the leaders presents a serious production problem in nurseries and Christmas tree plantations.

 

There are three effective suppression tools for reducing damage.  The first is the application of a “borer spray” to the terminals to kill the females before they lay eggs.  Effective products include those based on the active ingredients bifenthrin (e.g. Onyx), permethrin (e.g. Astro), or cyfluthrin (e.g. Tempo).  A second application may be required depending on spring weather conditions and product label recommendations.

 

If female weevils make it through the terminal insecticide applications, the second suppression tool is to remove and destroy infested terminals prior to the emergence of the next generation of adults later this season.  This will reduce the localized weevil population which is particularly effective where there are few conifer hosts growing in nearby forests or landscapes.  I’ll post a complete “how to” on this method later this season.

 

The third weevil management strategy is to make preventative systemic insecticide applications in the fall that target the weevils as they feed on the phloem the following spring. The systemics will also kill early instar larvae as they begin tunneling in the phloem but before they produce serious damage.  Systemics such as imidacloprid (e.g. Merit, Nuprid 1.6F, etc.) may be applied using soil drench or soil injection applications.  This preventative control measure should be reserved for landscapes, nurseries, or Christmas tree plantations that have a history of significant white pine weevil activity.

 

 

OHIO STATE UNIVERSITY EXTENSION

 

Where trade names are used, no discrimination is intended and no endorsement by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.

Ohio State University Extension embraces human diversity and is committed to ensuring that all research and related educational programs are available to clientele on a nondiscriminatory basis without regard to race, color, religion, sex, age, national origin, sexual orientation, gender identity or expression, disability, or veteran status. This statement is in accordance with United States Civil Rights Laws and the USDA.

CFAES provides research and related educational programs to clientele on a nondiscriminatory basis. For more information: [ http://go.osu.edu/cfaesdiversity ].

Any materials in this newsletter may be reproduced for educational purposes providing the source is credited.

 

BYGL Weekly News for December 10, 2018

BYGL Weekly News for December 10, 2018

 

The following articles were compiled during the last 7 days by members of the Extension, Nursery, Landscape, Turf (ENLT) team to benefit those who are managing a commercial nursery, garden center, or landscape business or someone who just wants to keep their yard looking good all summer.  Access the BYGL website for additional information on other seasonal topics at: http://bygl.osu.edu

 

For more pictures and information, click on the article titles.  To contact the authors, click on their names.

 

 

You’re a Mean One… Mr. Recluse?

Authors Ashley Kulhanek

Published on December 4, 2018

 

 

It’s the holiday season (the holiday season…) and many are digging in attics and basements for decorations and bows, stored sweaters, coats and yes… SNOW boots.  Inevitably, Extension offices receive calls about the unfortunate spider (or stink bug) that was found, dead or alive, while sifting through packages, boxes or bags that haven’t seen the light of day for a year.  The question is, “Is it a brown recluse?”

 

Remember that there are many different spiders that may come to inhabit our homes at one point or another, and cooler temperatures often facilitate home invasions from multiple insects and spiders alike. This includes some recluse look-alike spiders such as wolf spiders, funnel weaver spiders, and barn spiders.  These home invaders often make their way indoors for shelter, protection from the weather, or in search of food.  They are actually beneficial, providing pest control of other insects or arthropods you would rather not have, inside or out.  So, keeping them around is usually encouraged!

 

Brown recluse spiders (Loxosceles reclusa) are not known to survive winter outdoors in Ohio, but they do survive well indoors and can be dispersed through movement of furniture or household goods to areas outside their generally considered “range”.  Brown recluse spiders are secretive in nature.  As with many spiders, any undisturbed dark area could be a habitable space for them to hide out.  They, as with many other spider species, could inhabit garages, attics, basements and crawl spaces, behind wall voids, and hollow spaces.  Shed skins and egg sacs may be found near joists and tight protective spaces or under clutter, insulation, stored undisturbed boxes and stored clothing.  So when we run across any spider or critter that falls out of that artificial tree we just hauled upstairs, we often assume the worst.

 

They are named recluse for their shy and timid behavior.  People who come into contact with the poor creatures usually do so by stepping into a shoe or tossing on a stored item of clothing that has long sat and hasn’t been washed or shook out for a long time.  In the face of the impending SQUISH, the spiders must lash out and bite as their only last defense.  And this is how many spider bites have happened, regardless of species.  Most arthropods only bite or sting in defense during accidental crushing or agitation.

 

The identifying character most cited for Brown Recluse is the “violin” or “fiddle” shape on its back (cephalothorax).  This description is actually a little subjective and sometime people mistake stripes or other patterns as the so-called fiddle.  A better key to identifying the brown recluse is its eyes.  Brown recluse have only 6 small eyes arranged in three pairs on the head.  With legs extended they are about the size of a quarter.  They are tan to brown in color and appear semi-hairless though they do have short sparse hairs.

 

Here in Medina County, we have not had any confirmed samples brought into the Extension Office this season, which his not to say they could never be found.  But, in Richard Bradley’s “In Ohio’s Backyard: Spiders” he states, “This infamous family is represented by two RARE species in Ohio.”  But that’s not always the case for some of Ohio’s more southern counties.

 

General precautions for any home spiders concerns:

– Reduce clutter that serves as dark hiding places in basements, garages, and homes.

– Use gloves and wear long sleeves when unpacking boxes from storage.

– Be vigilant of what you are doing and where you are stepping in unfrequented spaces.  Use a bright flashlight to inspect dark corners you may be rustling around in if concerned about the presence of spiders.

 

For More Information, Check Out These Resources

Bradley, R. 2004. In Ohio’s Backyard: Spiders. Ohio Biological Survey.

Jacobs, S. 2015. Brown Recluse Spiders Factsheet.  Penn State Universityhttp://ento.psu.edu/extension/factsheets/brown-recluse-spiders

Potter, M. 2018. Brown Recluse Spider Factsheet.  University of Kentucky.  https://entomology.ca.uky.edu/files/ef631.pdf

 

More Information

University Of Kentucky

https://entomology.ca.uky.edu/files/ef631.pdf

Penn State University

https://ento.psu.edu/extension/factsheets/brown-recluse-spiders

 

 

 

 

2019 Commercial Applicator Recertification Conferences

Authors Jennifer Andon  Chrissy Kaminski

Published on December 3, 2018

 

 

  • Five hoursof recertification credits in one day!
  • Core credit available multiple times.
  • Fertilizer Recertification will be offered at Dayton, Sandusky and Columbus conferences.
  • All Categories will be offered.

Interstate reciprocity will be offered for the following states:  Indiana, Michigan, Kentucky, Pennsylvania, West Virginia.  Additionally, ISA and CCA credits will be offered for approved classes.

Exams will be offered at all four locations beginning at 10:30 am, for all categories.  Walk-in seats will be available. Please register for the exam by calling the Ohio Department of Agriculture at:  614-728-6978, or registering on-line at agri.ohio.gov.

 

2019 Commercial Recertification Conferences

 

January 9 (Wednesday)
Dayton Convention Center
Dayton, Ohio
 
February 22 (Friday)
Kalahari Conference Center
Sandusky, Ohio
January 15 (Tuesday)  
John S. Knight Center
Akron, Ohio
February 26 (Tuesday) 
Columbus Convention Center
Columbus, Ohio 

For Conference Questions, please go to pested.osu.edu or call OSU Pesticide Safety Education Program at 614-292-4070.

For Registration Questions, please call Walcom Registration Services at 740-524-4123

More Information

http://pested.osu.edu/commercialrecert

 

BYGL News – December 3

BYGL Weekly News for December 3, 2018

The following articles were compiled during the last 7 days by members of the Extension, Nursery, Landscape, Turf (ENLT) team to benefit those who are managing a commercial nursery, garden center, or landscape business or someone who just wants to keep their yard looking good all summer.  Access the BYGL website for additional information on other seasonal topics at: http://bygl.osu.edu

 

For more pictures and information, click on the article titles.  To contact the authors, click on their names.

An Unusual Insect-Killing Fungus

Authors Joe Boggs

Published on November 30, 2018

 

I received an e-mail message this past Wednesday from Tom Macy (Forest Health Program Administrator, Ohio Department of Natural Resources) concerning efforts to discover locations of the non-native elongate hemlock scale (Fiorinia externa) in Ohio and other states.  His message included two attached images taken by Bill Laubscher (Pennsylvania Bureau of Forestry) on November 20 that showed both the scale as well as odd looking blackened accretions on hemlock needles.

The file names for the images were Colletotrichum 1 and Colletotrichum 2.  I recognized the names as the genus of fungi that are associated with several plant diseases.  Indeed, if you Google Colletotrichum, you will find a number of plant-nasties including C. acutatum which is responsible for various anthracnose plant diseases.  At first, I thought Tom was reporting a fungal plant pathogen vectored by the scale.

However, Tom was sharing monitoring work in Pennsylvania by Bill Laubscher and Tim Tomon who also works for the Pennsylvania Bureau of Forestry.  The blackened accretions in Bill’s images showed fungal activity.  The fungus, C. fioriniae (formerly C. acutatum var. fioriniae), had sprung forth from the bodies of elongate hemlock scale.  The fungus had killed the scale making it an entomopathogenic fungus.

Of course, mycopathogens that kill insects is nothing new.  Notable entomopathogenic fungi include Entomophthora maimaiga which can dramatically decimate gypsy moth (Lymantria dispar) populations.  Such spectacular declines are known as epizootic events which are analogous to epidemics in human populations.

What’s fascinating to me is C. fioriniae is genetically closely related to fungi that are almost exclusively plant pathogens.  We often stress that plant pathogens don’t infect animals which remains true.  I’ve never known of anyone losing fingers to the fire blight bacterium or being pockmarked by anthracnose fungi.  However, I’ve never seen such a close genetic and thus taxonomic relationship between plant and animal pathogens.

On the other hand, C. fioriniae doesn’t behave like many other animal pathogens by simply jumping from one animal host to another.  Apparently, it hides out within hemlock needles as an endophytic fungus. The prefix “endo” means internal, or within, and the suffix “phytic” means plant.  This fungus has an intimate relationship with hemlocks and remains poised within the plant to spring forth and infect elongate hemlock scale.  It represents a case of mutualism with the fungus acting as natural protection against the scale.

It’s easy to imagine how this fungus may have evolved to infect a sedentary sucking insect.  The scale is a stationary target.  Once it settles and inserts its piercing-sucking mouthparts into the needles, it’s a sitting duck for fungal infection.  Perhaps the fungus is even sucked-up by the scale.

The potential significance of C. fioriniae as a biocontrol agent first came to light in 2002 with a widespread elongate hemlock scale epizootic event across several states including Pennsylvania, New York, New Jersey, and Connecticut.  Subsequent bioassay research published in 2009 showed this fungus is capable of producing mortality rates greater than 90% (See “2009 Journal of Insect Science” under More Information below).

 

Please Report

Thus far, we are uncertain of the exact geographical range of the non-native elongate hemlock scale in North America.  Also, we would be very interested to learn the extent of the fungal infections.

We need your help.  Take a close look at the images included in this report including those taken by Bill Laubscher in Pennsylvania on November 20.  Beyond its namesake host, elongate hemlock scale may also infest true firs, Douglas-fir, spruces, cedars, and occasionally pines and yews.  As with many armored scales on conifers, greater concentrations of scale bodies tend to be found on the older, inner needles.

If you find the scale, please report the exact location as well as the host.  Also, please note whether or not you see the blackened growth arising from the scale which indicates a fungal infection.  This is an “armored” scale meaning that it does not exude honeydew that becomes colonized by black sooty molds.

You can send your reports to me (just click on my name above to get my e-mail address) or to Tom Macy at:   Thomas.Macy@dnr.state.oh.us

More Information

2009 Journal of Insect Science

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3011895/

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