Good and Bad Birds on the Farm

Do you have a bird problem on your farm?  Do you want to encourage beneficial birds as an IPM tool? If so, consider attending this free webinar.  Registration information below:

Webinar: Supporting Beneficial Birds and Managing Pest Birds

Supporting Beneficial Birds and Managing Pest Birds

Webinar: Tuesday, October 1 at 11AM Pacific, 12PM Mountain, 1PM Central, 2PM Eastern Time

Register in advance at https://oregonstate.zoom.us/webinar/register/WN_Yey2HdAZQ8S3CSKUuR8FIg

Join eOrganic for the first webinar of our fall season! The topic is Supporting Beneficial Birds and Managing Pest Birds, by Jo Ann Baumgartner of the Wild Farm Alliance, Sara Kross of Columbia University, and Sacha Heath of the Living Earth Collaborative.

Beneficial birds can help farmers keep pest insects, rodents, and pest birds at bay. They act the same way that beneficial insects do in helping with pest control. The overwhelming majority of songbirds are beneficial during nesting season because they feed pest insects to their voracious nestlings. Farmers may be able to reduce their pest-control costs by providing habitat for these beneficial birds and by only targeting detrimental birds at the right time and place. Wild Farm Alliance and two avian ecologists will present on: a) How birds’ diets, foraging strategies, and nesting periods affect the farm, b) How best to manage and co-exist with pest birds, c) Why on-farm habitat and the surrounding landscape influences pest control, and, d) What farmers can do to make farms more bird-friendly and resilient. With this webinar and the associated Supporting Beneficial Birds and Managing Pest Birds booklet, we aim to help all farmers and farm consultants make the most of birds on farms.

Corn earworm remains abundant!

As detailed in VegNet on 24 August, we have seen very high numbers of corn earworm moths caught in pheromone traps since mid-August. Trap catch remained very high last week at most Ohio sites where we have traps. This pest prefers to lay its eggs on fresh-silking sweet corn but also can cause significant damage to tomatoes and bell peppers.

Our Ohio trap reports for corn earworm and several other vegetable pests are posted online, at this link: https://docs.google.com/spreadsheets/d/10gh3rHahdxLKkXQapGyEPxWsjHYRmgsezOoFHnwtyEo/edit?usp=sharing

One of the details shown on our trap report page is the type of trap. At most of our sites, we are using the type of trap called a Scentry Heliothis trap, which is a large cone-shaped trap made of white nylon mesh. At two of our sites, South Charleston and Columbus, we have the type of trap called a Hartstack or Texas Cone trap, which is the same shape but larger and made of metal hardware cloth. The Hartstack trap tends to catch much higher numbers of corn earworm moths, and tends to detect low density populations of corn earworm more effectively than the Scentry Heliothis trap. The Hartstack trap is not readily available from trap supply companies, thus we recommend the Scentry Heliothis trap to our cooperators. However for anyone who is interested in Hartstack traps, here are two tips. The plans for making your own Hartstack trap are shown in a fact sheet from Kentucky: https://entomology.ca.uky.edu/ef010 . We purchased our Hartstacks several years ago from a source in Illinois (see http://www.agrinews-pubs.com/news/building-a-better-bug-trap/article_c69e27e7-fa1e-58b5-b5f7-442112bfb2a0.html )

-Celeste Welty, Extension Entomologist

Increasing activity in corn earworm (tomato fruitworm)

Mid- to late-August is the time of year when we usually see a large increase in the populations of corn earworm, the pest that is also called the tomato fruitworm. As of last week, this trend has been seen in some parts of Ohio but not in others, which is unusual; we usually see an increase at all sites at this time of year. Our pheromone trap in Clark County jumped to 555 moths last week, up from 36 moths the previous week. Our pheromone trap in Franklin County showed an increase to 43 moths last week, up from 12 moths the previous week. The current moth population is likely composed of some recently immigrating moths from the southern USA as well as moths that emerged locally as the later generation of moths that migrated into Ohio back in early June.

Trap reports for corn earworm at several Ohio locations can be viewed using this link:  https://docs.google.com/spreadsheets/d/10gh3rHahdxLKkXQapGyEPxWsjHYRmgsezOoFHnwtyEo/edit?usp=sharing

Fresh-silking corn is the preferred host of the corn earworm, but tomato is another common host. It can also attack a variety of other crops, including bell peppers, lettuce, beans, potatoes, cole crops, cucurbit crops, as well as many weed species.

Infestation of the tomato fruitworm on tomatoes in Ohio is most likely in late August and September, but can sometimes occur much earlier, as has been seen this year. It prefers green tomatoes over ripening red tomatoes. Larvae often feed on one tomato fruit for a short time then move to another fruit. Damage in fruit appears as deep wet cavities. Eggs are usually laid on a leaf below the highest flower cluster.

Each female moth of corn earworm can lay 500 to 3000 eggs. Eggs usually hatch in 3-4 days but can be faster when weather is very hot. As the larvae feed, they progress through six instars or sub-stages, with each instar lasting 2-3 days. The larval stage lasts about 15 days at 86 degrees F. Once larvae are fully grown, they drop to the ground, where they tunnel 2-4 inches deep to pupate. The pupal stage lasts about 13 days. New moths start to lay eggs about 3 days after emerging from the pupal stage. The moths are active mostly at night, and hide in vegetation during the day. The moths feed on nectar in flowers of various trees and shrubs and weeds. The moths usually have a 5-15 day lifespan, but can live up to 30 days.

When corn is in the fresh-silk stage, it is attractive to corn earworm. During the time that Ohio’s large acreage of field corn is silking, our relatively small acreage of sweet corn and tomatoes is usually not attacked much by this pest. Once the field corn in any area begins to mature and dry, it is no longer as attractive to the earworms as late sweet corn and tomatoes. This year, much of Ohio’s field corn was planted later than normal due to frequent rains, so this protective effect of nearby silking corn has been happening later than usual this year but is now likely ending in most locations.

One of the most effective ways to monitor this pest is to use a pheromone trap to catch adult moths. As soon as the target moth is found in traps, fields of sweet corn and tomatoes and bell peppers should be scouted for signs of larval damage so that control measures can be taken in a timely and preventive manner.

In addition to the challenge of knowing when the corn earworm arrives, another challenge is its susceptibility to insecticides and transgenic crops. Observations over the past 12 years in the Midwest have shown that pyrethroid insecticides (Warrior, Brigade, and others) are not as effective at controlling corn earworm on sweet corn as they were previously. In years when the corn earworm population density is low, we have seen that pyrethroids can provide very good control, but in years when their density is high, pyrethroids are not very effective. Alternatives to pyrethroids for sweet corn are Coragen, Radiant, Blackhawk, Lannate, and Sevin. Alternatives to pyrethroids for tomato are Avaunt, Coragen, Exirel, Intrepid, Lannate, Radiant, Rimon, and Sevin. Among the transgenic sweet corn hybrids, we are seeing that the old Attribute hybrids are no longer very effective for caterpillar control, but the Attribute-II hybrids are very effective. Some growers are reporting that some of the Performance Series hybrids are not providing adequate control. We have a field trial in progress to determine how well the transgenic hybrids are currently working under Ohio conditions.

-by Celeste Welty, Extension Entomologist

Spider mite management

With hot and dry weather persisting over much of Ohio, there are reports of spider mite outbreaks on specialty crops. Because mites are tiny, they are often overlooked or misdiagnosed as a disease. Infested leaves have fine webbing on the leaf undersides. Tomato leaves damaged by spider mites usually have yellow blotches, while bean leaves show white stipples or pin-prick markings from mite feeding. Pumpkins can tolerate moderate levels of mites, but watermelons are more sensitive to injury from mite feeding. A simple method of diagnosing spider mites is to shake leaves over a piece of paper and look for moving specks that are visible to the naked eye. A closer look with a magnifier can show the tiny mites that are white, marked with two large dark spots on the middle of the body.

Mites have many natural enemies that kill them, such as specialized predatory mites or generalist lacewings, ladybugs, and pirate bugs, but these helpful predators are often killed by pesticides. Mites can be suppressed by periodic overhead irrigation.

Chemical intervention can be needed to keep the crop alive if spider mites are abundant. In some fields, the mite infestation is worst on a field edge by a dusty road. When a mite infestation is limited to field edges, infested fields should be scouted, and a miticide applied as a spot treatment to isolated infestations. Mite control is better when higher volumes of water are used; 25 to 50 gallons of water per acre is better than 10 gal/A.

Several pesticides are registered for spider mite control; some are restricted use, and some are for general use, as shown for vegetable crops in Table 1, and for hops and fruit crops in Table 2. At some locations, organophosphates are still effective for mite control, with Dimethoate being the best bet and MSR (Metasystox-R) as another choice. Dimethoate is an option for melons but is not allowed on squash or cucumbers; it has been a preferred product for mite control on soybeans. Dimethoate is prohibited from use on ornamental crops in high tunnels and greenhouses but is not prohibited from vegetable crops in high tunnels and greenhouses. Where organophosphates are not effective, Agri-Mek (abamectin) is generally the most effective product for mite control but it is a restricted-use product, while Acramite (bifenazate) and Oberon (spiromesifen) are nearly as good but are not restricted-use products. Other options for some crops are Portal, Envidor, Zeal, Nealta, Onager, Savey, Apollo, and Kanemite. Although Brigade (bifenthrin) and Danitol (fenpropathrin) are labeled for spider mite control when used at the high end of the rate range, they are generally not as effective as the true miticides. Dicofol is an old miticide that is still effective at some sites, but does not perform well at sites where resistant populations have developed. Vydate (oxamyl) is a Restricted Use product that is registered for use on eggplant for mite control. On organic farms, insecticidal soap (such as M-Pede or Des-X) can be used for mite control, but thorough coverage of the undersides of leaves is needed for good control. Soap can cause phytotoxicity if applied under sunny hot conditions. Soap is a good alternative in conventional fields that are too close to harvest to use a true miticide; insecticidal soap has a 12-hour re-entry interval and a 0-day pre-harvest interval.

-Celeste Welty, Extension Entomologist

What’s Chewing on my Sweet Corn?

While walking through a sweet corn plot this morning looking at how many plants were tasseling, I saw a few interesting things to quickly comment on in case growers are seeing these things in their fields.

I saw some rough chewing damage on the leaf and immediately thought, wow, it looks like we have some Fall armyworm in this plot (despite having a FAW pheromone trap nearby that has caught zero moths for weeks). Upon closer inspection, it was a grasshopper inside the rolled up leaf.  As I looked at the grasshopper, I noticed the frass around the leaf damage was not wet and messy typical of the pest but rather thinner, pelletized and fairly cylindrical. So even if the grasshopper had left the leaf, the “frass” would be a good clue it wasn’t a caterpillar.

Leaf damage caused by grasshopper.

As I began inspecting the tassels, I saw a lot of corn leaf aphid on just about each tassel. This sucking pest can be a problem if it exudes too much honey dew (sugary liquid waste excretion) on the tassel and it interferes with pollen shed and possibly pollination. While you can spray insecticides to knock down the aphids, be sure to take a look for natural enemies such as  ladybug adults and larvae, green lacewing larvae, and hover fly larvae.

Corn leaf aphid on tassel and ladybug adult (multi-colored Asian ladybeetle) feeding on aphids.

One of the biggest pests of sweet corn has been a little quiet for the past few months according to our trapping network, but we expect it to pick up in the next few weeks so be sure to have your corn earworm trap out near fresh silking corn with a fresh lure. See the nice summary below by Celeste Welty a few weeks ago with reference to spray frequency of CEW.

The corn earworm moths will be laying their eggs on (fresh) silks of sweet corn. Sweet corn can be protected from corn earworm infestation by insecticide sprays during silking. When the number of CEW moths caught in traps is moderate  (1 to 13 moths per day, or 7 to 90 moths per week), then sprays should be applied every 4 days if the daily maximum temperatures is below 80 degrees F, or every 3 days if the daily maximum temperatures is above 80 degrees F. More information about CEW, traps, and trap-based spray schedules is available using this link: http://u.osu.edu/pestmanagement/crops/swcorn/ .

Responses to Pumpkin/Squash/Melon Grower Stress Survey

On July 5th I posted an article acknowledging the difficult spring and early summer planting conditions most Ohio growers faced, and asked to let us (OSU specialists and Extension educators) know what kind of issues you were experiencing. Once these issues were identified, I began researching possible solutions in order to help growers salvage as much of the season and market as possible. Attached at the end of the article is a PDF with my responses to your questions.

I wanted to thank the 36 growers farming just over 500 acres who took time to respond to the survey. In general, most growers were delayed 2-4 weeks but had a crop in the ground now. The biggest concern besides the ability the control the weather, was that OSU specialists continue to post current information about crop management, pest management, and markets. Several articles along those lines have recently been posted to the VegNet Newletter and we will continue to do so, but if there is a specific topic that has not been addressed, please reach out and contact that specialist directly. Below is a list of OSU specialists and Extension educators with their contact information.

Best of luck to you for better weather this summer and a fair harvest this fall.

Specialist                    Area                            Contact

Doug Doohan              Weeds                        doohan.1@osu.edu

Celeste Welty              Insects                         welty.1@osu.edu

Sally Miller                  Diseases                      miller.769@osu.edu

Jim Jasinski                   IPM/Insects                  jasinski.4@osu.edu

Brad Bergefurd             Horticulture                  bergefurd.1@osu.edu

Matt Kleinhenz             Horticulture                  kleinhenz.1@osu.edu

Steve Culman                Fertility                         culman.2@osu.edu

In case you are not aware, we are having a Pumpkin Field Day on Aug. 22 at the Western Ag Research Station. Read more about it here http://u.osu.edu/vegnetnews/2019/07/25/pumpkin-field-day/

Response to Cucurbit Growers Early to Mid Season

 

Mid-summer insect observations

Corn earworm (CEW) showed a moderate surge of activity during this past week, from 19-22 July when our pheromone trap in Columbus caught 49 moths in a 4-day period. This follows a few weeks of low CEW moth catch, after high CEW moth catch in late June. A pheromone trap near Fremont caught 74 CEW moths this past week. The corn earworm moths will be laying their eggs on silks of sweet corn. Sweet corn can be protected from corn earworm infestation by insecticide sprays during silking. When the number of CEW moths caught in traps is moderate  (1 to 13 moths per day, or 7 to 90 moths per week), then sprays should be applied every 4 days if the daily maximum temperatures is below 80 degrees F, or every 3 days if the daily maximum temperatures is above 80 degrees F. More information about CEW, traps, and trap-based spray schedules is available using this link: http://u.osu.edu/pestmanagement/crops/swcorn/ .

The typical insect pests of mid-summer are currently being found on Ohio farms. Squash bug eggs and young nymphs are being found in squash and pumpkin fields. Cucumber beetles, both striped and spotted, are feeding in flowers of squash and melons. Squash vine borer is past its peak in terms of the number of adult moths caught in pheromone traps, which peaked in early July. The tobacco hornworm is feeding on tomatoes in the field and in high tunnels. Imported cabbageworm is feeding on cabbage and other Brassica crops. Colorado potato beetle adults are on eggplant and potato. Blister beetles are reported on potato. Sap beetles and western corn rootworm beetles are being seen on sweet corn. Japanese beetles are found on sweet corn, asparagus ferns, and various fruit crops, but they seem to be less numerous now than several weeks ago when huge numbers were seen.

The second generation of the European corn borer has not yet been detected, but it should start within the next week or two, and will be important in peppers and sweet corn.

An encouraging note is that many beneficial insects are also active in vegetable crops. Recent sightings include many Orius predatory bugs and the pink lady beetle in sweet corn, lady beetle larvae, lacewing larvae, the spined soldier bug, and damsel bugs in a variety of crops.

-Celeste Welty, Extension Entomologist

Corn earworm arrived early in sweet corn

Corn earworm has showed up unusually early this year and has been infesting early sweet corn that was not adequately protected. The earworm population as detected by moths caught in pheromone traps was very high in early June (161 moths in one trap in one week in Columbus), and again in late June at some sites (125 moths in one trap in one week). However, this past week, the number of moths caught dropped greatly (7 in one trap at Columbus). Similar trends have been reported from other parts of Ohio. As long as corn earworm moths are active, sweet corn fields that are in the early silk stage will become infested by corn earworm unless preventive measures are taken. The infestation will be less intense in sweet corn fields if the local fields of grain corn are in the silking stage, but due to the early summer rains causing delay in planting, grain corn in much of Ohio is not yet at the silking stage, thus sweet corn will be extra vulnerable to earworm attack. Once corn earworm is detected, silking sweet corn should be sprayed with insecticide every 2-6 days. The choice of an appropriate spray interval is as important as the choice of product to use. Details about the most appropriate spray interval based on pheromone traps are shown in the chart below.

Growers who do not yet have a trap can find information about buying a trap with this link: https://cpb-us-w2.wpmucdn.com/u.osu.edu/dist/1/8311/files/2019/07/TrapSpecsAndSources2019.pdf

and information about using the trap with this link:

https://cpb-us-w2.wpmucdn.com/u.osu.edu/dist/1/8311/files/2014/12/CornTrapInstructions2009-u47rp3.pdf

Our testing of insecticides for corn earworm control over the past 13 years has shown that pyrethroids (Warrior, Asana, Pounce, Mustang Maxx, Brigade, Baythroid, Hero) are generally effective for earworm control when the earworm population is low to moderate but generally not effective when the population is high. If pyrethroids are used, they should be used at the maximum labeled rate. Among pyrethroids, Hero is generally the most effective; it is a pre-mix of two different pyrethroids (Mustang Maxx and Brigade). Alternatives to pyrethroids are Coragen, Radiant, and Blackhawk, and the pre-mix Besiege, which was formerly called Voliam Xpress. Organic growers can use Entrust or a B.t. such as Javelin or Dipel.

For plantings of B.t. transgenic hybrids (the Attribute II series and the Seminis Performance series), we have found that the B.t. provides adequate control of corn earworm when populations are low, but not when earworm populations reach high density. These hybrids provide the best control when silks are fresh but less control when silks begin to dry. Thus insecticide sprays during the later part of the silking period are helpful to prevent earworm infestation in transgenic sweet corn.

-Celeste Welty & Jim Jasinski

Insecticide update for vegetable and fruit crops

There have been a few insecticide registrations that have come through since previous updates this past winter (summaries from January are available with these links: https://cpb-us-w2.wpmucdn.com/u.osu.edu/dist/1/8311/files/2019/02/PAT_Jan2019_1-page-1hvqfhg.pdf and https://cpb-us-w2.wpmucdn.com/u.osu.edu/dist/1/8311/files/2019/02/Summary_Jan2019_1-page-22nf965.pdf ).

Torac and Apta from Nichino America both contain tolfenpyrad as the active ingredient; both are in IRAC’s mode-of-action group 21A. Since March 2019, new crops on the new Torac label are onions and other bulb vegetables, lettuce and other leafy vegetables, and celery and other leaf petiole vegetables. Torac controls thrips, aphids, leafhoppers, flea beetles, and some caterpillars. Since February 2019, new crops on supplemental labels for Apta are strawberry and other low growing berries, raspberries and other caneberries, and blueberries and other bushberries. Apta controls thrips, plum curculio, fruitworms, Lygus (tarnished plant bug), and suppresses spotted-wing Drosophila.

Versys is a new insecticide from BASF that contains afidopyropen as the active ingredient, which puts it in IRAC group 9D. On the initial label in October 2018, the target pests were only aphids, as controlled at a low rate of product. A newer label now includes control of whiteflies at a higher rate of product.

Exirel is now allowed on raspberries and other caneberries, as shown on a supplemental label from November 2018. Use on caneberries is with a 1-day pre-harvest interval, for control of spotted-wing Drosophila and adult root weevils. Exirel is from FMC, and contains cyantraniliprole as the active ingredient, in IRAC group 28.

PQZ is a new insecticide product from Nichino America that has been registered since November 2018 but was missed in our earlier updates. PQZ contains pyrifluquinazon as the active ingredient. It is in IRAC group 9B. It controls aphids, whiteflies, and leafhoppers, and is allowed for use on Brassica head and stem vegetables, cucurbits, fruiting vegetables, leaf petiole vegetables, leafy vegetables, tuber and corm vegetables, as well as on pome fruit, stone fruit, and grapes.

Ethos-3D is a new insecticide/fungicide product from FMC that has been registered since 2018 but was missed in our earlier updates. It is for use on sweet corn. It contains bifenthrin (the same AI as in Brigade; IRAC group 3A) as the insecticidal component, and Bacillus amyloliquefaciens as the fungicidal component. It is for application at-planting for control of corn rootworm larvae, Asiatic garden beetle, wireworms, grubs, seedcorn maggot, cutworms, and armyworms.

-Celeste Welty, Extension Entomologist

Beware of thrips on strawberries

Although strawberries are not considered to be a vegetable crop, using VegNet is a good way to get information out to growers who have both vegetables and berry crops.

Strawberry fruit that have been injured by thrips are a dull or bronzed color, and are often small, hard, seedy, and fail to ripen. They can cause uneven maturity of fruit. When severe, their injury can make the strawberry crop completely unmarketable.

Thrips are an occasional serious pest of strawberries. This means that in most years, they are not a problem, but in some years, they can be a big problem. One such year was 2018 for some growers in Ohio. As far as we understand the problem, the reason for variability from year to year has to do with weather systems. In some years, conditions are right that large numbers of small insects such as thrips and leafhoppers are carried on strong weather fronts moving from the southern USA into Ohio during the time that strawberries are in bloom. In other years, this long-distance movement does not happen at all, or happens later, at a time when strawberries are no longer in bloom.

Thrips are small, slender, elongate, cigar-shaped insects, about 1 mm (1/25 inch) long. They differ from other insects by having narrow strap-like wings that are fringed with hairs (Figure 1). The wings are usually folded lengthwise over the back when they are resting or feeding (Figure 2). They have asymmetrical mouthparts (Figure 3) that have a well-developed left mandible and an underdeveloped right mandible. They feed by piercing plant cells by the mandible then sucking sap that oozes out of the punctured cells. Thrips generally have flowers as their preferred plant part. They are found in flowers of many species of plants. Thrips are often overlooked due to their small size and their tendency to hide in protected places. When present at low density, thrips are often not harmful to plants.

The thrips species that infests outdoor strawberries is Frankliniella tritici, which has the official common name of ‘flower thrips’, but which is widely known as the eastern flower thrips. It does not tolerate cold weather well so does not survive winter well in places like Ohio. The adults are yellowish brown, and the larvae are whitish-yellow. The larvae are similar to the adults in shape but smaller and without wings. On strawberries, the infestation starts by adult thrips during bloom but then can continue during fruit set by adults and their offspring larvae. Thrips hide under the cap of the berry or in grooves around the seeds on the berry.

A key to thrips management is frequent monitoring, at least once per week. Growers should examine early flower clusters on early cultivars. In each of five to 10 areas of the field, five to 10 blossoms should be tapped into a white cup, or into a zip-top sandwich bag, which should then be examined for the dislodged thrips running around on the surface. Count the number of thrips found, then calculate the average number of thrips per blossom. A rough action threshold for treatment with insecticide is the presence of 2 or more thrips per blossom. Once fruit are ¼ inch in diameter, an action threshold is 0.5 thrips per fruit. If thrips are above threshold, the trickiest part of management is to avoid spraying insecticide that will harm pollinators. Insecticide should be applied pre-bloom or before 10% of the plants have open blossoms. If thrips are found above threshold on early cultivars, then a preventive spray can be made on the later cultivars before their flowers open, to avoid harming pollinators.

Insecticides used to control thrips on conventional strawberries are Radiant, Assail, and Sivanto, all of which have thrips listed as a target pest on their labels. Thrips are well controlled by Lorsban, Brigade, and Danitol, which are allowed for use on strawberries, but thrips are not listed as a target pest of the label of these three products. Note that Lorsban has a 21-day pre-harvest interval. Products for thrips control on organic strawberries are Entrust and azadirachtin products such as Neemix and Aza-Direct.

If a biological control approach is preferred, several kinds of natural enemies are available for purchase from commercial insectaries for thrips control: Orius (predatory flower bugs), and two species of predatory mites: Amblyseius cucumeris and Ambylseius swirskii. Biocontrol is not feasible to begin once the thrips population is large but can be planned in advance at locations that have a consistent problem with thrips.

Figure 1. Typical appearance of a thrips.

Figure 2. A thrips with wings folded over its back.

Figure 3. Close-up of thrips head and mouthparts.

by Celeste Welty, Extension Entomologist