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.
Authors Joe Boggs
Published on June 22, 2018
I’m seeing large numbers of Japanese Beetles (Popillia japonica) in southwest Ohio. Compared to previous seasons, the beetles appear to be more evenly distributed; they are not hard to find. I’m hearing similar reports from the central part of the state.
I reported that beetles began to appear on the scene early last week which seemed a bit early [see BYGL Alert! “Masked Chafers and Japanese Beetles are on the Wing,” June 14]. It also seems early for high populations to be causing heavy feeding damage on leaves and flowers.
Japanese beetles were flying well below our radar prior to 2016 with rare reports of damaging populations. That began to change in 2016 when we saw some heavy localized populations in many areas of Ohio [see BYGL Alert! “Japanese Beetles Making a Comeback,” July 7, 2016].
The beetle revival continued last year. I reported that damaging populations were appearing in the southwest, central, and northeast parts of the state [see BYGL Alert! “Japanese Beetles Abound,” July 5, 2017]. Amy Stone (OSU Extension, Lucas County) wrote a follow-up report that high numbers of beetles were also being seen in northwest Ohio [see BYGL Alert! “More Japanese Beetle Abounding,” July 6, 2017].
Although Japanese beetles were widespread throughout the state in 2016 and 2017, their populations were highly localized. A short drive could take you from a location with high numbers to another location with virtually no beetles. Beetle populations seem less “patchy” this season with a widespread distribution and few “hot spots;” at least in southwest Ohio.
Damage is occurring on a wide range of host plants from sycamores to oaks to black locusts. Although it’s easy to identify Japanese beetle skeletonizing damage while beetles are present on favored hosts like grape, damage may be more difficult to diagnose later in the season particularly on less well-known hosts
A Look into the Crystal Ball
Are we seeing the beginning of general Japanese beetle outbreak? The short answer is we don’t know. The long answer is that despite being a non-native, Japanese beetles have started to behave like natives in some areas of North America with populations rising and falling naturally. As with native pests, there’s always the possibility for periodical outbreaks. However, outbreaks can be unpredictable.
Ever since Japanese beetles were first discovered in North America in 1916 in a nursery near Philadelphia in Riverton, New Jersey, they have been gradually moving westward. Trailing behind the beetles are a whole host of natural enemies. Where the beetles have been living for a number of years, such as in Ohio, the natural enemies are able to act on this non-native pest just like natural enemies act on native pests. So, populations can rise and fall dramatically from year-to-year. I believe that’s what we’re seeing: a “natural” population rise that I predict will eventually fall. How can I be sure? Because, we’ve seen it before.
Families- A Grouping or Gathering of Similar Plants
Authors Erik Draper
Published on June 22, 2018
Have you ever thought “why in the world should I care about plant families?” Or why does it matter if a plant belongs to a certain family? What if you were asked, “Can my Pyracantha (firethorn) shrubs get fireblight?” or “What other plants could be possible target hosts for the Emerald Ash Borer”? You will be able to understand the answers to these questions, IF YOU UNDERSTAND THE IMPACT OF PLANT FAMILIES! You can answer with confidence the question posed, “Why in the world are oleander aphids feeding on my Balloon Plant Milkweed (Gomphocarpus physocarpus)?
On July 10, 2018 from 10am to 3:30pm, in the Secrest Arboretum Jack and Deb Miller Teaching Pavilion, Paul Snyder, Jason Vail, Jim Chatfield and Erik Draper will help to answer why plant lovers should care about knowing plant families too. In this class session, we will discuss and look closely at the defining traits and characteristics of at least 15 different plant families commonly used in gardens and landscapes.
One key aspect to help with the identification of any plant is knowing the common traits of plant families and then we can ask the question “To which family does this plant belong?” Understanding plant family traits and characteristics leads to understanding what plants need to not only survive but actually thrive in a landscape setting. Each plant family has its own key characteristics like the number of flower petals, as well as the number and placement of stamens and pistils. These characteristics each contribute to the correct identification of an unknown plant and become very useful in resolving certain diagnostic dilemmas.
For example, plants in the Ericaceae family, all have a very specific site and soil pH requirement that is required to survive. If these requirements are brushed aside and ignored, these plants will, over a period of time, have their leaves gradually turn chlorotic, new twig extension will become shorter each year and eventually they will just die! Can you guess those requirements? Putting together a few members of the Heath or Ericaceae family helps to form an educated guess… So what do Kalmia, Vaccinium, Rhodendron, Einkanthus all require in order to survive? They all need extremely low soil pH’s, moist but not saturated soils, high organic matter content, and well-drained soils.
Come join us and learn more plant family facts that will help to boost your confidence in choosing those “landscape plants that you always wanted in the garden” to be a success!
Cost of the class, which includes outstanding lunch cuisine, is $40.00 per person. Contact Sarah Mays to register at 330-263-3831 email her at mays.201@osu.edu for more information.
Authors Joe Boggs
Published on June 21, 2018
Dodders are parasitic plants belonging to the morning glory family, Convolvulaceae. They were formerly placed in the dodder family, Cuscutaceae, with only one genus in the family, Cuscuta.
Depending on the reference, there are somewhere between 100 – 170 species worldwide with 13 species found in Ohio. The two most common species found in our state are Common Dodder (Swamp Dodder), C. gronovii, and Field Dodder, C. pentagona.
Just how common are dodders in Ohio? I don’t see them very often, but I welcome your input. Please be specific with pictures and exact locations.
For example, I’ve been keeping track of what appears to be a single dodder species in the Otto Armleder Memorial Park, Great Parks of Hamilton County, 5057 Wooster Pike, Cincinnati, OH 45226. All of the images and observations in this report were made at that location.
The hallmark of dodders are their thin, tendril-like stems that encircle the stems of their host plants. Dodder stems range in color from yellow to orange to red depending on the dodder species and age. Some, but not all species have tiny scale-like leaves. Although most dodders have some chlorophyll, it’s insufficient to photosynthesize enough sugar to support a singular lifestyle. Mature dodder plants also lack roots.
Dodders are obligate parasites; they can’t make a living without their plant hosts. They invade their hosts using specialized, peg-like structures called haustoria (singular haustorium). The dodder’s haustoria are considered modified roots and are used to extract water, carbohydrates, and nutrients from their host’s vascular bundles.
Of course, dodders do not start out looking like spent fishing line. They are annual flowering plants with each flower producing 2 – 4 large seeds depending on the species.
Apparently, there is no obvious seed dispersal mechanism for the large dodder seeds. Infestations in field crops and landscapes are often associated with the movement of soil, equipment, or water. Indeed, dodders are often found along waterways and Armleder Park is located in the Little Miami River flood plain.
The large dodder seeds are loaded with carbohydrate to support the frail seedlings until they can locate a plant victim. The seedlings produce a rudimentary root system, but if they don’t sniff out a host to latch onto with 10 – 15 days, they die.
I used “sniff out” deliberately because that’s exactly what they do. Research published in Science in 2006 showed that dodder seedlings are capable of detecting plant volatiles released by prospective host plants. The sensory mechanism used by dodder is not known, nor are the exact chemicals or mixture of chemicals that send an “eat here” message. However, it was shown that dodder can distinguish between odors emitted by good hosts like tomato and non-hosts like wheat.
What Lies Beneath
Dodders are stealthy plant invaders using a move that’s been described as mimicking a computer virus. Research published this year in Nature showed that dodders send microRNA into their hosts that silences the encoding of genes that would normally support defenses. One of those defenses is a protein that clots the flow of nutrients to the site of the dodder’s haustoria. Without the “anticoagulant” protein, the plants life blood keeps flowing into the dodder.
Dodder wreaks havoc on its plant hosts in other ways. The dodder bridge between several hosts can serve as a passageway for plant pathogens including viruses and phytoplasma. Plant stress caused by the heavy extraction of the host’s resources can weaken plants making them even more susceptible to plant pathogens as well as environmental calamities such as drought.
I may not see dodder as being widespread in Ohio; however, there is no doubt that dodder causes annual crop losses worldwide that are measured in tens of millions of dollars. These parasitic plants have been found sucking the life out of over 100 species of plants including alfalfa, clover, soybeans, and even solanaceous plants in gardens such as petunias and tomatoes.
The annual life cycle of dodder starting with seed germination in the spring means dodder can be managed using a range of preemergent herbicides. This is a common and effective approach used to suppress dodder in field crops and ornamental nurseries
However, research published in 2008 in the journal Flora casts some doubt that dodder always has an annual life cycle. The researchers observed a possible perennial characteristic of clover dodder (C. epithymum) by overwintering vegetatively on its most common perennial host Scotch heather (Calluna vulgaris).
I observed the possible harboring of dodder within the woody stems of black willow (Salix nigra) last fall. Dodder flowers were sprouting from woody nodules on the main stems. The flowers were free from any direct connections to dodder stems. I remain uncertain exactly what I was seeing and revisited the willows yesterday but could not find dodder tendrils emerging directly from the willow stems. However, I will be monitoring the trees this season.
Twisted Friends with Benefits.
Dodders have some nefarious sounding common names such as wizard’s net, devil’s guts, hellbine, and witch’s hair. However, they are not devoid of providing some benefits.
Research published in 2017 in the Proceedings of the National Academy of Sciences showed that dodder’s tangled threads can function as important lines of communication between connected plants. When a plant was attacked by defoliating caterpillars, messages sent to other plants connected on the dodder web caused them to raise their defenses. The caterpillars were less successful with attacking the pre-warned plants.
Dodders also contains a range of compounds that may be beneficial in human medicine. They have long been used in Chinese folk medicine. A review published in 2017 in Biomedicine & Pharmacotherapy reported dodders harbor molecules with possible therapeutic benefits including potential antiviral and anticancer activities.
Of course, some claims may be overblown. In preparing this report, I came across dodder facial cream that promises to reverse skin aging. I’m hoping to make a bulk purchase.
NOTE: See “More Information” below for key selected research referenced in this report.
More Information
2006 Volatile Chemical Cues Guide Host Location and Host Selection by Parasitic…
https://www.fs.fed.us/rm/pubs_other/rmrs_2006_runyon_j001.pdf
2008 Hidden in the host – Unexpected vegetative hibernation of the holoparasite…
https://www.sciencedirect.com/science/article/pii/S0367253008001278
2017 A Review on Phytoconstituents and Biological activities of Cuscuta species
https://www.sciencedirect.com/science/article/abs/pii/S0753332217313185
2017 Plants under stress by parasitic plants
https://www.sciencedirect.com/science/article/pii/S1369526616301819
2017 Stem parasitic plant Cuscuta australis (dodder) transfers herbivory-induce…
http://www.pnas.org/content/114/32/E6703
2018 MicroRNAs from the parasitic plant Cuscuta campestris target host messenge…
https://www.nature.com/articles/nature25027
Authors Joe Boggs
Published on June 19, 2018
Lace bugs do well in hot weather and they are certainly doing very well. I’m finding population densities and levels of damage that are normally seen in July. I posted a report on hawthorn lace bugs (Corythucha cydoniae) this past Saturday [see “Hawthorn Lace Bugs Affect More Than Hawthorns,” June 16]. This report highlights a few others.
Most lace bug species found in Ohio live on the lower leaf surface. They are tiny insects with the adults measuring no more than 3/16″ long. Lace bugs are so-named because of the lace-like pattern of veins and membranes in their wings. The nymphs are even tinier and appear to be covered in small spikes.
Both the adults and nymphs use their piercing-sucking mouthparts to suck juices from the leaves. Although feeding is done on the lower leaf surface, the damage appears on the upper leaf surface as tiny chlorotic spots (= stippling).
The first thing you may notice on infested trees are leaves with areas that look “bleached-out,” or leaves that are entirely white to light brown. High winds and heavy rains can drive lace bugs to lower leaves, so the damage may be heaviest in the lower canopy. Look closely to make certain you’re seeing stippling and not another plant problem such as powdery mildew.
The stippling may at first appear as distinct 1/4 – 1/2″ diameter spots on the upper leaf surface created by 1st instar nymphs feeding near the cluster of eggs from which they hatched. Eventually, the stippling will coalesce to produce large white patches as the damage becomes more widespread. Another feature of lace bugs are black tar-like fecal deposits that add to the unsightly appearance of heavily infested leaves.
Heavily damaged portions of the leaf, or entire leaves, will turn yellow to copper-brown. High lace bug populations can produce enough leaf damage to cause early leaf drop, branch dieback, and even the death of small trees and shrubs.
Lace bugs can also be a serious nuisance pest. They have a penchant for dropping from heavily infested trees onto unsuspecting hikers, picnickers, and patrons of outdoor bars and cafes. They don’t feed on people, but they can use their piercing-sucking mouthparts to deliver a pinprick bite particularly if they fall between a person’s neck and shirt color. Adding insult to injury, floating lace bugs can ruin a good Mai Tai.
A Rogues Gallery of Lace Bugs
Aside from the aforementioned hawthorn lace bugs, other lace bugs producing noticeable leaf damage in Ohio include: basswood lace bug (Gargaphia tiliae), buckeye lace bug (C. aesculi); oak lace bug (Corythucha arcuata), sycamore lace bug (C. incurvata); and walnut lace bug (C. juglandis). I’m also getting reports of chrysanthemum lace bugs (C. marmorata) on the rise in the central part of the state.
The buckeye, oak, and walnut lace bugs confine their feeding to their namesake hosts. Sycamore lace bugs may be found on American sycamore and to a lesser extent on London planetree. Basswood lace bugs feeds on all members of the Tilia genus; however, they have are particularly fond of silver linden (T. tomentosa).
Chrysanthemum lace bugs (C. marmorata) are unusual in two ways. They are found on both the lower and upper leaf surfaces and they may feed on a wide range of herbaceous perennials in the Asteraceae family including asters, black-eyed Susans, goldenrods, and sunflowers. These lace bugs may occur in greenhouses as well as landscapes. Indeed, landscape infestations may originate in greenhouses.
Management
The lace bugs in this report can have 2 to 3 generations per season in Ohio with leaf damage ramping up with each successive generation. This means it’s critical to target the current first generation with control measures to halt further damage this season.
Suppression includes simply applying a heavy jet of water to blast away the lace bugs. Of course, adults have wings, so they can fly back to trees meaning more “water treatments” may be necessary. Insecticidal soaps and horticultural oils are effective; however, direct contact is required. So, make sure to target the undersides of leaves. The same is true for pyrethroid insecticides; they are stomach poisons but lace bugs are sucking insects.
Some systemic insecticides such as acephate (e.g. Orthene, Lepitect) and the neonicotinoids dinotefuran (e.g. Safari, Transtect) and imidacloprid (e.g. Merit, Xytect) are effective against lace bugs. However, imidacloprid must be applied with enough lead-time to allow the active ingredient to migrate to the leaves in a high enough concentration to kill the bugs; it may be too late.
Of course, before using any insecticide, you must read and follow label directions paying close attention to plant safety as well as avoiding impacts on pollinators. This includes making certain sprays do not drift or runoff onto non-target flowering plants.
| A Most Beautiful Beetle
Authors Joe Boggs Published on June 18, 2018
Dogbane (Apocynum cannabinum) is the representative species for the dogbane family, Apocynaceae, which includes milkweeds and other plants that ooze sticky white sap ladened with poisonous alkaloids. Indeed, Apocynum translates to “poisonous to dogs,” or “dog killer.” Sap from dogbane is reported to have been used against ravenous feral dogs.
This is the time of the year when a close look at dogbane may reveal Dogbane Beetles; one of the most beautiful beetles found in Ohio. Indeed, the beetle’s scientific name, Chrysochus auratus, loosely translates to “made of gold.” This native beetle should be familiar to BYGL readers; it’s one of my favorite insects and I post at least one report about it each year!
The gorgeous iridescent beetles display a captivating array of colors that change with slight changes in your viewing angle. True to their scientific name, they may look like gleaming droplets of gold, or glisten with multiple mixed shades of green, copper, blue, and red.
The secret to the myriad display of colors can be found just below the surface of the 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. Dogbane beetles ingest the poisonous alkaloids (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. Using bright colors to send a warning message to enemies is known as “aposematic coloration.”
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