The Situation

I have heard from several growers and county agents that they have been seeing a lot of moldy ears lately.  Unfortunately, the drought in June followed by wet conditions in July and early August set the stage for ear rot fungi to infest corn this year. Ear rot diseases are Aspergillus ear rot, Diplodia ear rot, Fusarium ear rot, Gibberella ear rot, Penicillium ear rot and Trichoderma ear rot.  Pictures and symptoms and signs of each are below.

Aspergillus ear rot

Image by A. Robertson

Diplodia ear rot

Image by G. Munkvold

Fusarium ear rot

Image by A. Robertson

Starburst kernel pattern from Fusarium ear rot

Image by Pioneer Seeds

Gibberella ear rot

Image by A. Robertson

Penicillium ear rot

Image by A. Robertson

Trichoderma ear rot

Image by G. Munkvold

Damage Caused by Ear Rots

The most obvious losses due to ear rots are to yield and quality.  Probably the biggest concern with ear rots is that some of them produce mycotoxins that harm humans and livestock. Mycotoxin producers are Aspergillus ear rot (aflatoxin), Fusarium ear rot (fumonisin), Gibberella ear rot (deoxynivalenol or DON) and to a lesser degree Penicillium ear rot (PR toxin and Ochratoxin A).  Grain cannot be sold for food or feed if aflatoxin levels are 20 ppb (parts per billion), fumonisin levels cannot be higher than 30-50 ppb and DON no higher than 5 ppb.

Assessing Damage

Growers should hand pick 100 ears of corn from a representative area of a field and shuck them.   Pick out 10 ears showing the worst ear rot damage. Place these ears side-by-side to assess the average amount of kernel damage. If more than 25% of the kernels on these 10 ears are damaged, you have a problem.  If less than 25% of kernels on the 10 worst ears are damaged, check the field again after a rainfall event and plan on harvesting early. Harvesting at more than 20% moisture and drying to less than 15% moisture will significantly reduce harvest losses when compared to waiting for the corn to dry on its own in the field.  The extent of the problem can be determined by shelling all 100 ears, mixing the grain thoroughly, and sending a sample (usually 5.0 lbs) to a reputable mycotoxin testing facility.  Don’t mix grain from a field affected by ear rots with grain from a field that has not been affected.

What to do if You Have 10% or More Affected Ears

• Harvest early at higher moisture and dry to below 15% moisture
• Adjust combine to discard light or damaged kernels
• Clean harvest equipment between affected fields and clean fields
• Segregate poor quality grain from good grain
• Store affected long-term grain at less than 13% moisture and 30°F or below
• Don’t store affected grain for more than 1 year

By: Tom Kuhar, Alejandro Del Pozo, and Katlyn Catron. 

Summer storms moving up from the South often bring pests with them.  Fall armyworm (FAW) is definitely one of them, and true to form, this tropical moth pest has shown up around Virginia, causing problems in various crops as well as turfgrass.  We noticed FAW attacking whorl-stage sweet corn in Blacksburg three weeks ago, and recently have heard reports of problems in Richmond and Appomattox.  Other colleagues have documented the presence of FAW in Williamsburg and the Hampton Roads. Fall armyworm is a tropical moth native to warm climate areas of the western hemisphere.  It cannot successfully overwinter in Virginia, but frequently makes its way to our state by flying at high altitudes where populations get carried northward on wind fronts.  Turfgrass, pasture grass, late planted sweet corn and sorghum, and fall small grains plantings can be particularly at risk to damage from this pest. 

Crops at risk.  This pest seems to have a very wide host range, with over 80 plants recorded, but clearly prefers grasses. In addition, field crops also can be attacked, including alfalfa, barley, Bermudagrass, buckwheat, cotton, clover, corn, oat, millet, peanut, rice, ryegrass, sorghum, soybean, sugarcane, timothy, tobacco, and wheat.  When the larvae are very numerous, they defoliate the preferred plants, acquire an “armyworm” habit and disperse in large numbers, consuming nearly all vegetation in their path. Just like a battle front, FAW damage appears in a characteristic progressive line across grass plantings (Fig. 1).

Monitoring. Because of the unpredictability of pest pressure from year to year and throughout the season, the use of pheromone traps to monitor local presence and build-up of FAW levels of these moth pests is strongly recommended.  Pheromones are natural compounds that are emitted by female FAW moths to attract male moths (Fig. 2) for mating. Synthetic compounds that mimic natural FAW pheromones, often referred to as lures, are placed in traps to attract and trap male moths to inform farmers if FAW is present in their fields and if there is a need for increased scouting. Funnel or bucket (unitrap, universal trap [see Fig. 3]) is the preferred trap for FAW moths.  We are monitoring FAW in different locations around Virginia and have caught moths at all locations (Fig. 4).

In-field scouting for turfgrass. If you are unsured that you might have an active FAW infestation, you could use the soap flush method, to drench a designated area and disturb the caterpillars that are present. Below are suggested steps to conduct a step-by-step soap flush drench.

What do I need to scout for FAW?

–           03 gallons of water per lawn

–           Liquid dish soap (our suggestion is to use a lemon-scent soap)

–           Measuring utensils

How do I start?

–           Mix 3 tablespoons of the dish soap in one gallon of water

–           Then pour one gallon of the soap solution over 2 squared-foot area of the lawn

What is next?

–           Spend at least 5 minutes observing the areas of the lawn where you pour the soap water

–           Be patient, it takes some time for these caterpillars to move up from the thatch, since the dish is an irritant for them

–           There will be several insects and other arthropods crawling out from this area

–           Remember to look for caterpillars with the “Y” suture on the front of their heads to confirm the presence of fall armyworms

–           Repeat this drench technique in a total of three different spots in one lawn

Control. Most fall armyworms that established in Virginia will die naturally from diseases, parasitoids, and predation, and virtually none will make it through the winter., Nonetheless, masses of larvae can cause significant feeding damage to turfgrass in just a day or two, and thus quick mitigation is sometimes needed to stop their attack. This invariably involves insecticide applications.  A wide range of products are available for control of FAW, but resistance to certain insecticides has been reported in some populations and control of large larvae is sometimes difficult with any insecticide.  Pyrethroids appear to still be working well on FAW as well as most of the newer lepidopteran-targeting insecticides like diamides (i.e., Acelpryn in turfgrass, Coragen and Vantacor in agricultural crops) and spinosyns (Radiant, Entrust, Blackhawk in ag crops, Matchpoint in turfgrass etc.). 

A few disease issues have popped up within the past week on peanuts and soybeans. Some are pretty routine and some are not…

Peanuts

As you may expect, the wet, humid weather has been favorable for peanut diseases like leaf spot, southern stem rot (white mold) and Sclerotinia blight, but especially leaf spot. Sclerotinia is moving slowly due to the warmer weather over past two weeks, but with highs in the 70s today and possibly going forward I expect it to move faster. I have observed Sclerotinia blight in my trial plots. This late in the game I prefer Omega 500 for Sclerotinia blight over Miravis + Elatus. Miravis may not perform against leaf spot if there’s any out there already and Elatus is not a good stand-alone product for Sclerotinia. Remember, if you use Omega 500 you must use a leaf spot material with it. With leaf spot, just don’t extend your spray interval beyond 14 days. The leaf spot advisory has shown leaf spot risk to be steadily high and the last effective spray date jumps 2 days every day. If leaf spot is already showing up you may want to use a micronized sulfur product to temporarily arrest leaf spot along with a fungicide that gives residual control. The hot weather we experienced up until now has led to southern stem rot (white mold) showing up in some fields. If this is the case the best products for that are Excalia (3.0 fl oz), Elatus (7.0 – 9.0 oz) or Convoy at 32 fl oz.

Soybeans

Warm humid weather have led to outbreaks of FLS (frogeye leaf spot) and target spot in some fields. Frogeye will show up first in soybeans that have poor resistance to FLS, and some soybean varieties are more susceptible to target spot like AG49XF3. Both diseases can be very similar in appearance but FLS shows up more in the upper canopy and target spot starts in the lower canopy. I have seen pictures of soybeans defoliated from the bottom up by target spot recently. If you sprayed ahead of disease symptoms you shouldn’t have many problems, but you may see target spot start showing up. If you see disease is already there, use products that have an effective Group 3 fungicide that have curative disease activity. Examples would be Delaro Complete, Lucento, Revylok and Topguard or Topguard EQ.

If you have questions or concerns contact me via e-mail at dblangston@vt.edu or use my cell phone at (757) 870-8498.

By: Tom Kuhar and Brian Currin, Department of Entomology, Virginia Tech.

Early sweet has had its challenges this year in Virginia for sure. First the weather. A drought in June was hard on a lot of crops, but definitely corn if you weren’t able to irrigate. Following that up, a series of rainfall events almost every day in some locations for some stretches in July made it hard to spray insecticides on sweet corn in a timely manner. In addition to challenging weather, pest pressure has been unusually high. We are not even out of July yet and corn earworm moth numbers have been higher than usual in central and western Virginia this month in 2024. Moth catch in pheromone traps totaled 192 and 286 moths per trap last week in Montgomery County (western part of the state) and Halifax County (south central Virginia), respectively. That’s pretty high for July. Harvested sweet corn last week from Whitethorne, VA was heavily infested with corn earworms (Fig. 1) and later corn in the whorl stage had higher than usual infestations of fall armyworm (Fig. 2). This pest species usually comes later in the season. This year some early summer storms brought FAW moths from the south to Virginia.

Many sweet corn growers rely on insecticide spray programs to protect their ears from worm infestations. Some corn earworm populations have shown reduced susceptibility to pyrethroid insecticides such as lambda-cyhalothrin, bifenthrin, Hero, Baythroid, Asana XL, etc. Currently the top performing insecticide products with regards to corn earworm control in sweet corn include: Coragen, Coragen Evo, and Vantacor (all contain the same diamide active ingredient). These insecticides are also relatively safe on nontarget organisms like vertebrates, bees, and natural enemies. Beseige and Elevest also include the same diamide active ingredient paired with a pyrethroid. They are very effective, but less safe on beneficial organisms. The spinosyn products Radiant and Blackhawk are also fairly effective as is the old carbamate standby, Lannate LV. This older insecticide has performed well in recent efficacy trials in sweet corn. These are pretty much it when it comes to effective insecticides for sweet corn. All of these insecticides should be used in a rotation with other products. Recent insecticide trials have shown that rotating the aforementioned products with pyrethroids every other spray provides decent control. This may not be the case in areas that are showing high levels of insecticide resistance.

Table 1 shows an action threshold for spray intervals based on trap catches of moths. Our moth catch has been high in late July suggesting a short interval between sprays is probably needed.

Table 1.  Action thresholds and insecticide spray intervals during silking based on pheromone trap catch of CEW moths using the Scentry nylon mesh trap and Hercon Heliocoverpa zea lure.
Average number of CEW moths captured per trap			Recommended control action or days between sprays
per day	per 5 days	per week
less than 0.2	less than 1	less than 1.4	spray at green silk then reassess
0.2 – 0.5	1 – 2.5	1.4 – 3.5	6
0.5 – 1	2.5 – 5	3.5 – 7	5
1 – 13	5 – 65	7 – 91	4
>13	>65	>91	3

Barley yellow dwarf virus (BYDV) is a significant threat to small grains worldwide and is currently impacting winter wheat in Virginia. This virus is transmitted by cereal aphids. In addition to wheat, BYDV can also infect barley and other perennial grassy hosts, including forage crops such as tall fescue. Yield losses to BYDV often do not exceed 30-35%; however, excessive losses have also been reported in some regions.

Our ongoing survey in Virginia is indicating a widespread BYDV infection. Nearly all the samples tested in 2024 have been positive for BYDV. These samples were received from Augusta, Culpeper, Essex, Prince George, Shenandoah, Montgomery, Northumberland, and Nottoway counties.

Symptoms

BYDV symptoms include reddening or yellowing of leaves (starting from the tip and leaf edges), reduced root biomass, and decreased stem height, ultimately affecting yield and grain quality (Fig. 1). These symptoms also resemble those of other conditions; therefore, laboratory testing is needed to confirm BYDV infection.

Management

Once infected, there is no remedy for the affected plants. However, a combination of cultural and chemical approaches can help minimize the risk of BYDV spreading.

Managing weeds and volunteers can eliminate BYDV and aphid reservoirs. Late fall planting provides an opportunity for the young seedlings to evade infestation by aphids that are on the move from reservoirs. Seed treatment with systemic insecticides combined with late planting are expected further to minimize the risk of BYDV infection in the fall.

Infections that occur in the spring are not expected to result in significant losses since plants often outgrow BYDV infection.

Mapping BYDV distribution in Virginia

We are currently investigating the distribution of BYDV in Virginia and evaluating factors that can predict the risk of BYDV incidence. You can contribute to our ongoing research by sending plant samples for BYDV testing; samples will be tested free of charge. Your participation will help us better understand the prevalence and transmission dynamics of BYDV in Virginia, enabling us to develop targeted management strategies to mitigate the risk of BYDV incidence in agricultural landscapes.

Please fill out this form and include it with your plant samples.

This article is prepared by Shirin Parizad.

As most of you know, corn earworm is a devastating pest of many crops in Virginia.

This native moth pest can successfully overwinter as pupa in Virginia when winters are relatively mild. Virginia crops will also get the usual dispersal of moths coming up from the southern states after mid-July that will lay eggs on many crops that flower in late summer.

Last week Mr. Bill Tiver from Halifax County reported 10 moths per night in his corn earworm trap placed on his farm and larvae already infesting some of his earliest sweet corn. In addition, VCE agent Helene Doughty, in Cape Charles, VA on the Eastern Shore recorded high numbers in the corn earworm moth trap placed there. This is definitely some early warnings of a potentially bad corn earworm year. We most definitely had higher than usual insect overwintering success in Virginia this year.

Greetings friends across Virginia. My graduate student, Hannah Swarm, is researching the ecology and management of wireworms in Virginia. Wireworms are the subterranean larval stage of click beetles and can be quite damaging to many crops including potato, sweetpotato, corn, grains, carrot, hemp, to name a few.

For one of her research objectives, we are hoping to document the different species of wireworms that are found in the different regions of the state (Coastal, Piedmont, mountains).

If you happen to have a decent field where we could come visit and dig around the outside perimeter and collect wireworms, we would greatly appreciate it. Please, email us: hannahswarm711@vt.edu and tkuhar@vt.edu. We are collecting during the months of April and May. Many thanks.

Commercial vegetable producers have a new tool to assist with integrated pest management (IPM) of diseases and insects in vegetables. MyIPM for Vegetables is the newest resource in the MyIPM app series (https://myipm.app/) for smartphones and smart devices. It currently includes modules for diseases and insects of cucurbits and tomatoes, and additional vegetable crops are planned to be added in the future. Modules contain images and descriptions of diseases and insects; information on available chemical, biological, and cultural management methods for each disease/insect; and tables of labeled fungicides and insecticides that include active ingredients, product names, FRAC/IRAC codes, efficacy, application rates, preharvest intervals (PHIs), and restricted-entry intervals (REIs). Links to additional resources may also be included.

App content is focused on commercial vegetable production in the southeastern U.S., but users outside the southeastern U.S. and home gardens may also find information in the app useful. The development of MyIPM for Vegetables content was led by vegetable entomology and plant pathology specialists from universities within the southeastern U.S. who are part of the Southeastern Vegetable Extension Workers (SEVEW). The SEVEW are also responsible for the popular Southeast U.S. Vegetable Crop Handbook (www.vegcrophandbook) that has been a key resource for commercial vegetable producers in the southeastern U.S. for over 20 years. Author and image credits for specific disease or insect profiles and pictures are available at http://myipm.app/vegetabltes.

MyIPM for Vegetables is not intended to replace product labels. It is meant to be a tool to help vegetable producers make informed IPM decisions. Pesticide users should always read and follow label instructions prior to use. Product labels may change. Product rates may differ depending on the site of application (e.g., field or greenhouse) or type of application (e.g., foliar-applied or soil-applied. Check product labels for additional instructions, precautions, and/or restrictions not listed in the app. Also, check the state registration status of products prior to purchase and use; products may not be registered for use in all states.

MyIPM for Vegetables is free to download for Apple (Apple Store) and Android devices (Google Play). Content is downloaded directly to phones/devices; an Internet connection or cellular signal is not required to access content once it is downloaded. Updates, however, do require an Internet connection or cell signal, and notifications will pop up when updates for downloaded modules and the appropriate Internet/cell connection is available. The MyIPM series began with MyIPM Fruit & Nut that was originally developed by Clemson University in 2012 for peaches and strawberries; the app has since expanded to include other small fruits, tree fruits, and pecans. Other apps in the series include MyIPM Row Crops and MyIPM Hawaii. The Southern Region IPM Center maintains the databases for the MyIPM series apps.

Acknowledgement

This work is partially supported by the Southern IPM Center (Project S23-043) as part of the USDA National Institute of Food and Agriculture Crop Protection and Pest Management Regional Coordination Program (Agreement No. 2022-70006-38002).

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Prepared by Dr. Rebecca A. Melanson, Associate Extension Professor, Plant Pathology, Central Mississippi Research and Extension Center; Dr. Thomas Kuhar, Department of Entomology, Virginia Tech; Dr. Tom Bilbo, Coastal Research and Education Center, Clemson University; and Ms. Inga Meadows, Department of Entomology and Plant Pathology, North Carolina State University.

EPA has finally issued a statement on the revocation of tolerances for chlorpyrifos. For this year, 2024, chlorpyrifos can be used on all product labeled crops. In 2025 and beyond, it will only be allowed on 11 specific crops; alfalfa, apple, asparagus, cherry (tart), citrus, cotton, peach, soybean, strawberry, sugar beet, and wheat (spring and winter). However, there will be further state restrictions on those 11 tolerances coming soon (e.g. chlorpyrifos will only be allowed on tart cherries in MI).

———- Forwarded message ———
From: U.S. EPA Office of Chemical Safety and Pollution Prevention oppt.epa@public.govdelivery.com
Date: Fri, Feb 2, 2024 at 1:23 PM
Subject: EPA Update on the Use of the Pesticide Chlorpyrifos on Food
To: dlfrank@vt.edu

EPA Update on the Use of the Pesticide Chlorpyrifos on Food
The U.S. Environmental Protection Agency (EPA) is issuing an update on the use of the pesticide chlorpyrifos on food.

Chlorpyrifos is an organophosphate insecticide used for a large variety of agricultural uses, including soybeans, fruit and nut trees, broccoli, cauliflower, and other row crops, as well as non-food uses. In a final rule issued in August 2021, EPA revoked all tolerances for chlorpyrifos, which establish an amount of a pesticide that is allowed on food. This action effectively stopped the use of the pesticide chlorpyrifos on all food and animal feed. EPA took this action in response to an April 2021 order from the U.S. Court of Appeals for the Ninth Circuit for the Agency to issue—within 60 days—a final rule addressing the use of chlorpyrifos in food or feed crops, without taking public comment or engaging in “further fact-finding.”

That tolerance revocation rule was challenged by a chlorpyrifos registrant and several grower groups in the U.S. Court of Appeals for the Eighth Circuit. On November 2, 2023, the Eighth Circuit issued a ruling vacating EPA’s final rule and sending the issue of chlorpyrifos tolerances back to EPA for further proceedings. The ruling did not include a timeframe or specific instructions for EPA to take a final action on the use of chlorpyrifos in food or feed crops without public comment.
EPA is issuing a technical correction in the Federal Register that changed the Code of Federal Regulations to reflect the Eighth Circuit’s decision. The Eighth Circuit’s mandate issued on December 28, 2023, finalized the court’s judgment and vacated the Agency’s 2021 rule revoking chlorpyrifos tolerances.

Since the tolerances are currently in effect, growers can now use currently registered chlorpyrifos products on all crops with reinstated tolerances, consistent with directions for use on those product labels. However, such uses may be subject to restrictions by individual states.

The Eighth Circuit’s decision stated that EPA should have considered modifying the tolerances in addition to complete revocation and noted that the Agency had “identified 11 specific candidates” of food and feed crop uses whose tolerances could be modified in a Preliminary Interim Decision EPA issued in 2020. Thus, the Agency expects to expeditiously propose a new rule to revoke the tolerances for all but 11 uses with additional restrictions for geographic location and rate of application to address safety of the tolerances, and potential restrictions for farmworker and other vulnerable populations, and vulnerable species and their habitats. Those 11 uses are: alfalfa, apple, asparagus, cherry (tart), citrus, cotton, peach, soybean, strawberry, sugar beet, wheat (spring), and wheat (winter). These 11 uses were identified in the December 2020 Chlorpyrifos Proposed Interim Decision and represented about 55% of the total chlorpyrifos usage (average annual pounds applied) on agricultural commodities between 2014-2018.

EPA is also engaged in discussions with registrants of chlorpyrifos products to further reduce exposures associated with these 11 uses of chlorpyrifos. EPA will also consider the 2020 Proposed Interim Decision and public comments received on that document.
At this time, any existing final cancelation orders, including any terms for sale, distribution, and use of existing stocks of products subject to those cancelation orders and related return programs for chlorpyrifos products, remain in place, unless and until amended by EPA.
EPA will continue to update the public as it evaluates and takes any actions related to chlorpyrifos use.
For more information, view the Federal Register Notice.