From Daniel Frank (Virginia Tech Pesticides Program):

As of February 28, 2022, all food tolerances for chlorpyrifos were revoked and any new applications of chlorpyrifos will render any food treated as adulterated and ineligible to be distributed in interstate commerce. In issuing the final rule, EPA found that it could not determine that there is a reasonable certainty of no harm from aggregate exposure, including food, drinking water, and residential exposure, to chlorpyrifos, based on currently available data and taking into consideration all currently registered uses for chlorpyrifos. EPA has a dedicated webpage including information for anyone in possession of chlorpyrifos products for use on food when tolerances expire. According to EPA,
• Applicators should discontinue use on food. If the products label allows for use in other non-food settings, it may continue to be used for those non-food purposes.
• Chlorpyrifos products should not be disposed of in landfills for industrial or municipal solid waste.
• Current options for dealing with chlorpyrifos products labeled for use on food:
o Store chlorpyrifos products until there is an opportunity for appropriate disposal. Details on proper storage can be found using the following links:
 https://www.epa.gov/safepestcontrol/storing-pesticides-safely
 https://www.epa.gov/pesticide-worker-safety/requirements-pesticide-storage
o Appropriately dispose of these products as specified by the state.
Information regarding the VDACS pesticide collection program including the 2022 service area and dates/times of collection were previously sent out and are also available here. Should any additional information become available related to the rule including other options for final disposition of the product, I will be sure to share that information.

Regards,

Daniel

—
Daniel L. Frank
Director of Pesticide Programs
Virginia Tech
302 Agnew Hall
460 West Campus Drive
Blacksburg, VA 24061
540-231-3430
vtpp.org

By: Tom Kuhar, Alejandro Del Pozo, and Sally Taylor
Virginia Tech Department of Entomology

In the past week, many areas of Virginia have experienced severe outbreaks of fall armyworms (FAW), which have completely destroyed lawns, sod plantings, hayfields, and alfalfa fields. As you would imagine, we have gotten a lot of calls about these pests. We’ve included some of the FAQ below.

1.  Who’s being harmed the most by armyworms?
   
   Lawns with turf-type fescue grass are being hit the hardest across Virginia.  Alfalfa and hayfields are also being attacked.  

2. What crops are at risk? 
While FAW are known to attack a number of crops such as grasses, small grains, corn, sorghum, soybean, and vegetables, this particular strain of FAW seems to be a bit more selective.  Several people have reported FAW only eating the fescue grass and leaving behind crabgrass and other plants and weeds. Kentucky bluegrass, and Zoysiagrass for example have not appeared to have been damaged.  There have also been very few reports of FAW in late-planted sweet corn, which is often a magnet for FAW.  So, we are not sure exactly what crops might be at risk from this current strain of FAW.  We are advising to keep a close watch on all susceptible host plants. 

3. Does climate change play a role in spreading armyworms? If so, how?
Fall armyworms are tropical moths.  They cannot survive cold winters.  With climate change, it is possible that these moths are overwintering a little further north than usual.  If climate change leads to dry (drought) conditions in the southern states, then high densities of these moths can build up.  When storm winds blow north, they carry the moths to the mid-Atlantic, northeast, and Midwestern states. 

4. What do you think the rest of the year will look like in terms of armyworms? Is the worst behind us or yet to come?
Great question.  The fall armyworm will complete a full generation of its life cycle (egg-larvae-pupa-adult moth) in about 30-40 days, depending on weather conditions.  This fall armyworm outbreak occurred early enough for the moth population to still cycle through another generation here in Virginia, meaning more eggs might be deposited on lawns and more devastation from larval feeding may occur.  However, FAW are very susceptible to disease that occurs after wet rainy conditions, which we’ve also experienced.  So, we may see things go either direction.  Still don’t know. 

5. Have there been previous years where we’ve seen a similar explosion in army worms? Is this going to be the ‘new normal’ having FAW every year?

We last had a fall armyworm outbreak in 2018.  It was not as severe.  This is the worst FAW devastation that I’ve seen in Virginia in my 30-year career in entomology.  We still do not know if we might have another huge outbreak of FAW in 2022. All we know that some insect pests have cycles between outbreak. It could be possible that with warmer and dryer conditions, we might see FAW being present in higher number during the upcoming years. Now we know that this creature can come in Virginia as early as late-August. Scouting for this pest will be still crucial.

6. What can you do about them? 

If lawns have been killed, the only recourse is to reseed the lawn this fall.  If new fall cover crop plantings have been devoured, then reseeding those also may be the only recourse.  For crop protection, insecticides recommended for control include most pyrethroids (active ingredients such as bifenthrin [in the products Talstar, Brigade, Sniper, and many others]), lambda-cyhalothrin, and commercial products such as Mustang Max, Baythroid XL, and others), the carbamate, Lannate LV, and many of the more selective (lepidopteran-targeting) insecticides such as the diamides Prevathon, Coragen, Acelepryn, Besiege, indoxacarb products like Steward, Avaunt eVo, Provaunt, the active ingredient spinosad (in products such as Blackhawk, Tracer, Matchpoint), and other products including Radiant, or Intrepid Edge.  Consult the relevant Pest management Guide for specific recommendations on the various commodities.  Please note that control of large larvae may be difficult with any insecticide.  Link to the VCE Pest Management Guides for Field Crops, Vegetables, and Turf are provided below.  On turf, we have gotten very good control of FAW larvae with pyrethroids, which are also one cheaper insecticide options.  Golf course turf treated with a systemic diamide insecticide like Acelepryn or Tetrino have shown no damage even after 50 days post-spray. 

Links to Pest Management Guides   https://resources.ext.vt.edu/

Turf:  

https://resources.ext.vt.edu/contentdetail?contentid=2377&contentname=2021%20Pest%20Management%20Guide%20-%20Home%20Grounds%20and%20Animals

Field Crops:      

https://resources.ext.vt.edu/contentdetail?contentid=2375&contentname=2021%20Pest%20Management%20Guide%20-%20Field%20Crops

Vegetables:  

https://resources.ext.vt.edu/contentdetail?contentid=2379&contentname=2020-2021%20Mid-Atlantic%20Commercial%20Vegetable%20Production%20Recommendations

By: Drs. Tom Kuhar, Alejandro Del Pozo, and Sally Taylor (Dept. of Entomology, Virginia Tech)

Recently, some VCE agents as well as golf course superintendents in the northcentral and southwestern counties of Virginia have reported fall armyworm outbreaks (Fig. 1) on lawns and golf courses.  This outbreak is earlier than usual and potentially could lead to one of the heaviest pest problems that we’ve experienced from this pest in Virginia in recent years. Some lawns have completely been destroyed by these voracious feeders (Fig. 2 and 3).

Fig. 1. Fall armyworm larvae collected from a lawn in Richmond, VA. August 26, 2021. Photo courtesy of Jeff Sacks.

Fig. 2. Fall armyworm destroyed lawn in Henrico Co. August 26, 2021. Photo courtesy of Jeff Sacks.

Fig. 3. FAW damage to lawn in Richmond, VA. August 26, 2021. Photo courtesy of Tyler Green.

 It’s important to understand the biology of this polyphagus pest (Fig. 4).  Fall armyworm (Spodoptera frugiperda) is a tropical moth native to warm climate areas of the western hemisphere.  It cannot successfully overwinter in Virginia.  However, fall armyworm moths (see Fig. 9) are strong fliers, and populations can show up throughout the eastern United States in the late summer and fall months, sometimes in very high populations like we saw most recently in 2018 in Virginia, and now in 2021.  Female FAW moths can lay up to 10 egg masses (each with 100 – 200 eggs) (see Fig 4).  So, huge densities of armyworms can build up from just a few egg laying moths in a field.  This can completely destroy lawns or new plantings of grain cover crops.    

Fall armyworm can feed on a number of different host plants, but prefers grasses, small grains, corn, and sorghum. 

Control

Insecticides recommended for control include most pyrethroids (such as bifenthrin, lambda-cyhalothrin, as active ingredients, and some commercial formulations such as Mustang Max, Baythroid XL, etc.), the carbamate (Lannate LV) and many of the more selective (lepidopteran-targeting) insecticides such as the diamide Prevathon, Coragen, Acelepryn, Besiege (as commercial formulations), indoxacarb products like Steward, Avaunt eVo, Provaunt, spinosad products such as Blackhawk, Tracer, Matchpoint, and additional insecticides such as Radiant, Intrepid Edge, as well others.  Consult the relevant Pest management Guide for specific recommendations on the various commodities.  Please note that control of large larvae is sometimes difficult with any insecticide.  Link to the VCE Pest Management Guides for Field Crops, Vegetables, and Turf are provided below.  On turf, we have gotten very good control of FAW larvae with pyrethroids, which are also one the cheaper insecticide options. 

Links to Pest Management Guides   https://resources.ext.vt.edu/

Turf:  

https://resources.ext.vt.edu/contentdetail?contentid=2377&contentname=2021%20Pest%20Management%20Guide%20-%20Home%20Grounds%20and%20Animals

Field Crops:      

https://resources.ext.vt.edu/contentdetail?contentid=2375&contentname=2021%20Pest%20Management%20Guide%20-%20Field%20Crops

Vegetables:  

https://resources.ext.vt.edu/contentdetail?contentid=2379&contentname=2020-2021%20Mid-Atlantic%20Commercial%20Vegetable%20Production%20Recommendations

Sources

http://entnemdept.ufl.edu/creatures/field/fall_armyworm.htm

Luginbill P. 1928. The fall armyworm. USDA Tech. Bull. No. 34.

This week, my PhD student, Sean Boyle, observed pickleworm holes in our zucchini and squash in Whitethorne, VA near Blacksburg. This is the first that we’ve seen this pest in 2020. If you have noticed this pest in your area, please let me know – email tkuhar@vt.edu. The pickleworm, Diaphania nitidalis (Stoll) is a tropical moth pest of cucurbit crops including pumpkins, squash, and cucumbers (Fig. 1). It is typically a pest in the southern U.S. and does not overwinter in Virginia. The past few years, the pest has made its way northward in late summer on wind and storm fronts. Several pumpkins growers in Virginia have suffered damage from this pest in since 2017 usually following some August summer storms.   

Moths fly to flowering pumpkins, squash, or cucumbers and deposit their eggs. A single female moth can lay up to 400 eggs usually on cucurbit flowers.  Larvae feed on flowers (Fig. 2) and bore into fruit leaving a characteristic perfectly round hole often with sawdust-like fecal material around it as well.     

Management. Pickleworm is very difficult to predict or monitor for as eggs are very tiny, moths fly at night, but are not attracted to lights, and there is no commercially-available pheromone lure.  As a result, cucurbit growers in the South often apply insecticides weekly during the fruiting stages until final harvest.  Pyrethroid insecticides can be effective at controlling this pest if sprayed in a timely manner (i.e., lambda-cyhalothrin, permethrin, bifenthrin, Baythroid XL, Mustang Max, etc.). Pyrethroids are often used because of their low cost and because they also control squash bugs and cucumber beetles, but they are not IPM compatible and can result in outbreaks of secondary pests such as aphids.  Usually two or more sprays of pyrethroids in late summer can cause severe aphid problems leading to honey dew build up on plants. Other insecticides that control pickleworm include: the spinosyn productss, Radiant and Entrust, the diamide insecticides, Coragen and Harvanta, the insect growth regulator (IGR) Intrepid, and the lepidopteran-targeting insecticide Avaunt eVo.  All of these products will have less nontarget impacts than pyrethroids and will also control pickleworm.                                                                                           

This article was co-authored by Virginia Tech Entomology Ph.D. student, Kadie Britt.

Here are the corn earworm moth catch numbers from a handful of pheromone traps that we have set up in hemp fields and one sweet corn field around Blacksburg, VA. Trap catch appeared to peak around mid-August with moths emerging from cornfields and has subsided a little toward the end of August. Crops such as soybeans, hemp, tomatoes, and sweet corn are still at risk to this important pest.

Corn earworm (CEW) is the insect pest of greatest concern to hemp grown outdoors in Virginia and other states. For more information about this pest’s biology and behavior in hemp, see this factsheet: https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/ENTO/ento-328/ENTO-328.pdf.

We have already started to see worms feeding on hemp throughout Virginia. CEW feeding on hemp causes mechanical damage to buds, allowing environmental pathogens to enter crop material, ultimately leading to bud rot. Bud rot is visible and present in hemp crops right now but is not prevalent just yet. Managing populations early on will be key to reducing crop injury this season.

Strict regulations on pesticide applications to hemp prevent the use of many available insecticides. We have conducted a laboratory experiment to evaluate the efficacy of some products that are currently allowed for use in hemp in Virginia as well as Pyganic, which is not labeled on hemp, but is a widely used organic insecticide.

Treatments included in the August 19, 2020 bioassay included:

1. Untreated control (UTC): water
2. Agree: Bacillus thuringiensis subspecies aizawai strain GC-91
3. Spear-Lep + Leprotec: GS-omega/kappa-Hxtx-Hv1a + Bacillus thuringiensis variety kurstaki
4. XenTari: Bacillus thuringiensis subspecies aizawai strain ABTS-1857
5. PyGanic: Pyrethrins
6. PyGanic + PBO (insecticide synergist): Pyrethrins + Piperonyl butoxide

To conduct this bioassay, corn earworm larvae (3^rd to 5^th instars) were collected from untreated sweet corn grown at Kentland Research Farm in Whitethorne, VA. Untreated hemp seed heads were collected from grain hemp, variety ‘Joey’, grown at the Urban Horticulture Center farm in Blacksburg, VA. Seed heads were dipped in spray tank concentrations of each insecticide at the high labeled rate and placed into 1 oz. diet cups. Larval corn earworms were placed directly on top of treated material. Mortality was evaluated at 1, 2, 3, and 4 days after the experiment was set up (Figure 3). PyGanic + PBO provided significantly greater efficacy against CEW than all other products tested with only 6.5% of worms surviving after 4 days. The addition of the synergist is needed for effective control with Pyganic due to pyrethroid resistance development in this pest.  Unfortunately, Pyganic is not currently labeled for use on hemp in Virginia.  Agree, XenTari, and PyGanic without PBO all performed similarly with 50.3%, 53.5%, and 59.9% of worms surviving after 4 days, respectively.

Looking ahead this season, insecticide research trials in CBD hemp will be conducted in Blackstone with all of the aforementioned products plus many more. We will continue doing lab bioassays with CEW and other insecticides that are allowed for use in hemp at this time. Results will be shared as they become available.  

Over the past couple of weeks our fruiting vegetable crops at Kentland Farm in Whitethorne, Virginia have been invaded by abundant numbers of leaf-footed bugs (Leptoglossus spp.). These bugs that are in the same bug family Coreidae as the squash bug Anasa tristus. They are piercing sucking feeders that have killed entire cucumber and zucchini plants from their feeding on stems and leaves or have caused numerous puncture wounds on fruit, which result in a little fluid oozing from the fruit.

These insect pests can be controlled using the same insecticides that are labeled for use on stink bugs and squash bugs, namely, pyrethroids or neonicotinoids for conventional growers. Organic growers can achieve some suppression of bugs with the use of products containing pyrethrins such as Pyganic or Azera, or with the use of Surround (kaolin clay powder), which also works to prevent sunscald on fruit.

To learn more about this pest, please see the following VCE fact sheet that we produced a decade ago. Wow has it been that long? https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/3012/3012-1522/3012-1522_pdf.pdf

Since early July, we have been monitoring Heliothis traps baited with corn earworm pheromone at on 4 hemp fields and one sweet corn field in and around Montgomery, Co., Virginia. Below are the trap catch results. After a week or two of low catch, the moth activity has picked up especially at the Wall sweet corn.

Corn earworm moths per trap per week

FMC Corp. just released a new insecticide Elevest WITH RYNAXYPYR® ACTIVE and BIFENTHRIN. This new insecticide should be available in late season 2020. According to the label, Elevest is registered for use on corn, soybean, edible bean, sweet corn, peanut, cotton, potato and a few other crops. Similar to the product Besiege, Elevest is a mixture of a Group 3A pyrethroid (bifenthrin) with the diamide Group 28 insecticide chlorantraniliprole, which is found in the popular products Coragen or Prevathon. Thus, it will be effective on a wide range of insect pests.

Corn earworm larva in mature sweet corn ear.

Corn earworm is the major pest attacking corn ears in the mid-Atlantic U.S. Moth activity has been high in some areas of Virginia such as the Eastern Shore based on pheromone trap catches and grower reports in fields. Sweet corn is one of the most preferred host plants for corn earworm, especially if fresh silks are available when female moths are ovipositing.

For control in sweet corn, it is recommended to begin treatment when the ear shanks emerge or the very first silks appear. Silk sprays should continue on a schedule based on pest pressure on the farm or area blacklight or pheromone trap counts, geographical location, and time of year. This time of year (August) it may be necessary to treat on a 2-3 day schedule.

Dr. Sally Taylor (Tidewater AREC) and I have seen increased levels of pyrethroid (insecticide class 3A) resistance in CEW populations throughout Virginia, and that these insecticides should be used with caution and rotated to other insecticide classes within a season.  See the list of recommended insecticides in the table.

During heavy populations and high temperatures, treatments will need to be made according to the legal “days to harvest” of the chemical. For best control during heavy infestations, maximize the gallonage of water per acre, use a wetting agent, and make applications during the early morning if possible. If irrigation or rains wash off the spray within 24 hrs after an application, repeat treatment as soon as the foliage dries.

Bt Transgenic Sweet Corn

Bacillus thuringiensis (Bt) sweet corn hybrids are available that express single or pyramided insecticidal proteins for protection against lepidopteran “worm” pests. Attribute® hybrids (Syngenta Seeds) expressing the cry1Ab protein (YieldGard trait) have been available since 1998, and these hybrids now express the Liberty Link herbicide tolerance trait. Performance Series™ hybrids (Seminis Seeds) expressing two Bt proteins (cry1A.105 and cy2Ab2) are also available and these have the RoundupReady gene as well. However, based on multiple years of field trials in Virginia and surrounding states, neither of these Bt traits/varieties provide effective control of CEW due to Bt resistance development to the Cry proteins.  Thus, fields planted in these Bt hybrids will need insecticide applications, depending on the insect pressure and level of resistance in the population. In addition, under moderate to high moth activity (early August-early September), many eggs are laid later in ear development after the expressed Bt protein has degraded in dead silk tissue. This loss of protein activity also is accelerated by hot, dry conditions, which cause rapid desiccation of the silk tissue. As a result, earworms and fall armyworms have a greater chance of surviving and invading the ear. Under high moth activity, up to 50% or more of the Attribute ears can become infested with larvae. In this situation, spray schedules of 3 or 4 applications starting 3-4 days after the first onset of silking and repeated 3-4 days apart may be required.

Attribute® II Bt corn hybrids (Syngenta Seeds) with pyramided genes expressing YieldGard and Viptera traits (Vip3A protein) and stacked with the Liberty Link trait are now available. This Bt pyramided gene technology currently provides outstanding nearly 100% control of all lepidopteran pests of sweet corn.