Author Archives: Sally Taylor

About Sally Taylor

Please contact Sally if you have insect pest management concerns in field crops. email: phone: 919-801-5366

Aphids in alfalfa

Large aphids populations have been observed in alfalfa this year following insecticide applications targeting alfalfa weevil. If you haven’t scouted for alfalfa weevil in Virginia, you should. See the bottom of this post for a weevil summary.

Aphids, typically pea aphids, can be problematic when their natural enemies are disturbed. They can reduce vigor and cause wilting in first cuttings. If early cutting is not an option, several insecticides (mostly pyrethroids) are labeled for their control. Low label rates are generally effective as long as you ensure good coverage. Scout for aphids by pulling 30 random stems per field and counting the number of aphids. This guide from Iowa State can help you make treatment decisions.

Most of the aphids I have seen in Virginia alfalfa are pea aphids (left) and cowpea (right). If you think you have another species, please give me a call or send an email.

Photos Erin Hodgson, Iowa State

My thanks to Lane Grow from Southern State Cooperative for his ongoing efforts to scout and report problems in western Virginia.

Alfalfa weevil information

Scout fields by pulling 30 random stems and inspecting foliage for weevils. Weevil larvae are small, can be white, yellow, or green, and have black heads. They are often tucked tight into new growth. It’s possible to dislodge larger larvae so be careful or collect stems into some container that catches these. I use a plastic freezer bag and insect stems in the shop or truck. This guide from Penn State can help you make spray decisions. Cutting alfalfa is an option if you don’t want to use pesticides. I recommend using clorpyrifos based on spray tests in 2018 and 2019. Some people have been successful with indoxacarb (Steward) or pyrethroids (many brand-name and generic options). Coverage is essential with any product.


Finishing out the soybean crop – when you can safely stop spraying

Soybean loopers have reared their ugly heads across southeastern and coastal Virginia this week. With many of us busy hauling corn, it is reasonable to ask  – when can we stop spraying beans?

In a normal year, we could safely ignore mid-September infestations. This year, the majority of double crop Virginia fields are completing pod fill. Research indicates that R3-R5 beans benefit from a spray when defoliation reaches 15% and you find more than 1 looper per sweep. I recommend that you at least double, and can safely triple, this threshold in R6 beans (i.e., 35-50% defoliation is acceptable). It benefits you to exercise restraint when treating fields after R5.5. There is no scenario when you need to spray R7 beans for loopers. Cooler evening temperatures will work in our favor when they arrive.

In Virginia, Intrepid Edge and Steward have been our most consistent treatments (see image below from 2017). Looper populations in Virginia have tested diamide resistant the past two years (e.g., Besiege, Prevathon). Spraying pyrethoids  will only make the problem worse.


mid-season cotton insect managment

Plant bugs continue to be a problem in some Virginia fields with ¼ of those scouted by the entomology team above threshold for the first two weeks of bloom. In anticipation of the upcoming bollworm flight, Monsanto sponsored a meeting last week at the TAREC to discuss mid-season insect management in cotton. Here is a summary of our discussion:

  1. For 2 gene cotton (Widestrike, Bollgard II, Twinlink): scouting for eggs is recommended. Sample 100 terminals and leaves. Aim for 10 in 10 locations in the field. If you find 25 eggs, spray an insecticide. I recommend Prevathon unless stink bugs or plant bugs are an issue in your field. In that case, use Besiege. Bollworm (Helicoverpa zea aka corn earworm) and tobacco budworm (Heliothis virescens) eggs are indistinguishable and budworms are 100% controlled by Bt cotton. There is some risk that you are spraying unnecessarily. Very low numbers (<3%) of larvae sampled in non-Bt cotton were budworms in 2016 and 2017.
  2. For 3 gene cotton (Widestrike 3, Bollgard III, and Twinlink Plus): scouting for 2nd stage larvae  (1/8″ or larger) is recommended. This gives in-plant toxins time to kill small worms. Sample 100 bolls, blooms, and/or squares. Aim for 10 in 10 locations per field. If you find three larvae in one trip, two larvae in two consecutive trips (two larvae in each trip), or one larva in three consecutive trips (one larva in each trip), spray insecticides. I do not anticipate damage in 3 gene cotton unless we have very high pressure.
  3. Pyrethroids have performed poorly in cotton in 2016 and 2017 tests (15-50% control). I think that pyrethroids are too risky in cotton. Some growers are satisfied with the control that they have been achieving. Last year, worm specific products ran out in some Virginia locations. I recommend Steward as an alternative to Prevathon and Besiege for bollworm control in cotton.
  4. Weekly scouting is recommended for all pests. Bollworm eggs hatch fast (2-3 days) and worms cannot be controlled by any product once they are inside of the boll.
  5. Spray bugs only at threshold. Bloom threshold for plant bugs is 2-3 per drop cloth sample. For stink bugs, use damaged fruit thresholds: Week of bloom 1 = 50% internal boll damage; week 2 = 30%; weeks 3, 4 and 5 = 10%; week 6 = 20%; week 7 =30%; week 8 = 50%. About a dozen beneficial insects are common in Virginia cotton. Ambush bugs, big-eyed bugs, minute pirate bugs, green lacewings, two species of ladybird beetles, and several types of spiders are examples. They are of two types: 1) predators that prey upon an insect pest (see examples below), or 2) parasites that live within the host insect. These insects, particularly the predators, reduce the number of eggs and larvae of bollworms, plant bug nymphs and aphids. Because these allies lessen the impact of pest insects, common sense dictates that producers use them as a management tool. Their presence often means that growers can delay and, on occasion, eliminate some insecticide applications. However, the rapid increase in pest populations will often overwhelm the beneficial population and applications become necessary. Do not hesitate to spray pest insects at recommended thresholds.

A big thank you to Seth Dorman and his scouting crew and to Glenn Roundtree for initiating and organizing our recent pest management discussion.

Corn earworm found in Virginia peanut fields

Peanut scouts in Suffolk today found fields with above threshold numbers of corn earworm/tobacco budworm (4 per row foot). Fields previously treated recently with chlorpyrifos may be at higher risk because they have fewer beneficial predators.

Black beat cloths can aide in sampling. However, shaking and slapping plants will dislodge worms onto soil for easy counting. Make sure and check around the base of the plant when using either method.

Feeding damage shows up in the form of holes in foliage. Worms may also feed on terminals and flowers so scouting for damage alone is not recommended. Peanuts can lose a lot of leaf material without losing yield, but drought-stressed or herbicide injured plants are at higher risk for yield-loss. Do not spray unless necessary. Recent dry weather in combination with broad-spectrum insecticides can flair spider mites.

Pyrethoids are a common choice for earworm control in Virginia and most products can be tank mixed with a fungicide to save money. Always read and follow label instructions. Pyrethroids are losing efficacy against earworm and we have experienced spray failures in other crops (soybean, cotton, sweet corn). Budworm have been resistant to pyrethroids for some time. You will not be able to distinguish these two species in the field. Refer to NCSU video for details. Do not expect complete control of large worms or high populations. Alternative products labeled in peanut include Prevathon, Besiege, Steward, Radiant, Intrepid Edge, and Blackhawk. A list of products and rates is included in Virginia Tech’s Pest Management Guide.

Plant bug control in blooming cotton

Tarnished plant bugs continue to be a problem in some Virginia cotton fields. This week, scouts found 14 of 32 fields over the pre-bloom threshold (8 per 100 sweeps) and increasing numbers of nymphs. Drop cloth sampling is recommended for blooming cotton and counting squares is no longer a good indication of feeding. Threshold is 2-3 bugs per sample. Check out this short video ( if you have questions on how to use this method or are unsure of what nymphs look like. Dirty blooms indicate feeding, but active populations should be confirmed before a spray is made.

As cotton begins to bloom, neonicotinoids (e.g., Admire Pro, Centric, Belay) lose efficacy and I recommend rotating to a pyrethroid, a pyrethroid/acephate mix, or Bidrin. These products will  also control stink bugs if present. Transform is not labeled in Virginia, but our representative in Richmond is working hard to get us a Section 18 and I hope to have one in place by next year at the latest. All of these products will kill beneficial predators in your field. This is a concern as we near bollworm egg lay in cotton.

I encourage you to treat for insect pests only when thresholds are reached. Plant bug control will likely be needed through mid-August when populations peak, even in fields that have been previously sprayed. Spider mites, aphids, and bollworm (in two-gene cotton) risk increases with each broad-spectrum insecticide use, as does the risk for sprayer fatigue.

Special thanks to graduate student Seth Dorman and crew for their continued scouting efforts.

Plant bug scouting report – Week 2

A team led by graduate student Seth Dorman scouted 34 VA fields for plant bugs this week. Plant bugs were found in all but 4 fields, 6 fields were over threshold. Prior to bloom, fields require treatment if you find 8 plant bugs in 100 sweeps AND less than 80% square retention.

Nymphs are increasing in number. Young nymphs are small (aphid-sized) and thus, can be harder to scout for. They will be captured in sweep nets – be mindful when checking the bottom of the net. I recommend sampling with a black beat cloth later in the season to help identify nymphs in blooming cotton.

I will continue to provide updates and recommendations as cotton begins to bloom in our area. My thanks to Seth Dorman and team for their continued effort.

Start scouting cotton now for tarnished plant bug

Black squares and missing squares are a sign that plant bugs have fed in your field. Scout to determine if they are still active.

Tarnished plant bug (TPB) has begun its annual migration into Virginia cotton. PhD student Seth Dorman scouted VA cotton fields this week (image below) that were over pre-bloom thresholds (indicated in red).

Plant bugs can be found in every VA cotton field from the first square on, but it does not pay to spray unless they are causing damage. Use thresholds when determining what fields to treat and use a sweep net to sample multiple places in a field since populations are not evenly distributed. Prior to bloom, fields require treatment if you find 8 plant bugs in 100 sweeps AND less than 80% square retention. Adults are highly mobile and can reinfest quickly following applications. It may be tempting to spray only later in the season. If you are above threshold, this decision will lower your yield.

Impact of different spray timings on yield. Spraying at any point in the season yielded higher than unsprayed cotton. Thresholds are as effective as weekly sprays and will save you money. The damage potential in late-plated cotton is higher.

Important considerations for this season include:

1) Late-planted cotton is at higher risk. This picture from last season shows that losses in late-planted cotton (Jun 1) are much greater than in early-planted cotton (May 1).

Effects of different spray timings on lint yield are much more apparent in late-planted cotton. Spraying for plant bugs at threshold will save money and increase yield regardless of planting date.

2) Spraying at threshold is as effective as weekly sprays and costs less money. Spraying only early (pre-bloom) or only late (>5th week of bloom) are the least effective spray timings.

3) Rotate insectides. Some populations in the Suffolk area are surviving high doses of acephate and bifenthrin. If your cotton is squaring, thrips treatments are no longer needed and acephate should be left out of the tank. I recommend using a neonicotinoid product pre-bloom (clothianidin, thiamethoxam, or imidacloprid). Check the label and use the highest allowable rate. Neonicotinoids will not provide adequate control after cotton has bloomed.

Seth’s team will continue to scout VA cotton counties and we will post distribution updates and management recommendations as the season progresses. I would like to thank Seth for his hard work on this problem. If you have concerns, please contact me.

armyworm in VA small grains

I have received several reports from Virginia Beach and Chesapeake of armyworms infesting wheat and hay in large numbers. Neighboring regions of NC are experiencing similar outbreaks.

Overall, these infestations are rare in our state, but scouting is recommended. Fields treated previously with pyrethroids may be at higher risk because they contain fewer natural enemies to combat pest outbreaks. Armyworms feed at night and may be found under residue and at the base of plants during the day. Oftentimes, they can be seen curled into a c-shape (see photos below). Thresholds are one larvae (0.75 in or longer) per linear foot in barley and 2-3 per foot in wheat. Refer to Chapter 4 of Virginia Tech’s “Pest Management guide: Field Crops” for products and rates labeled for armyworm control in our state. Pay attention to PHI before making an application. Pyrethroids can be effective against armyworm. Good coverage is critical, especially in high residue fields.

Photos courtesy of JB Rigg, Helena Chemical.

Small upsurge in kudzu bug populations

Kudzu bug has been spotted above threshold (1 nymph per sweep – use at least 15 sweep samples in multiple parts of the field) in south central Virginia and in parts of central North Carolina. Kudzu bugs typically move into soybean in July-August in our state. Distribution surveys conducted by the entomology department in 2016 showed that kudzu bug are present in many soybean growing regions of our state.

Please consider the following information before making the decision to spray for this pest.

  1. Wait until nymphs (nymphs are wingless and cannot fly) are present in the field. Adults can make multiple invasions into a field. You do not want to make repeated sprays for this pest.
  2. Insecticides labeled for kudzu bug are broad-spectrum and will kill beneficials in your field. We are experiencing a large and early corn earworm flight this year in Virginia. Worm pests are much more likely to be a problem in fields that have been previously sprayed.

I’ll keep you posted on what we are seeing in soybean throughout Virginia. Please call if you have something to report.

Sally 919-801-5366

Large bollworm flight this year into VA cotton

If blacklight traps at the Tidewater AREC in Suffolk are any indication, we are currently experiencing an unusually large and early bollworm (aka corn earworm) moth flight this year. Average trap catches over the past 4 nights have averaged 70 moths per night. I have included 2016 season-long catches below for comparison.

We have additionally scouted for, and found, eggs in cotton and on silks of late-planted corn. I have included pictures below to help with identification. Our ongoing corn earworm survey has revealed large numbers of worms completing development on Bt corn in multiple counties. I strongly encourage cotton growers who planted Widestrike or Bollgard II this year to be vigilant when scouting fields. In agreement with Dominic Reisig’s (North Carolina State University) 2016 recommendations, entomologists in the Mid-South (Angus Catchot – Mississippi State University) have suggested egg thresholds broken-down by trait package:

WideStrike Cotton: Treat on 10-15% egg lays on bloom tags

BG2 cotton: Treat on 25-30% egg lay on bloom tags.

These thresholds are supported by observations made across the Southeast last year, including in North Carolina and Virginia, that worms have a higher chance of surviving on blooms than on any other part of the plant. These thresholds have not been established through experimentation and I consider them to be extra protective. Budworm eggs are identical to bollworm eggs and this species is controlled by Bt toxins. I have seen both budworm and bollworm moths in cotton this year.

Some growers have planted conventional cotton this year. We have established egg and larval thresholds in Virginia for non-Bt varities:

Eggs: 10 eggs per 100 terminals or 2 eggs per 100 fruiting forms (most cotton we have scouted has reached this threshold)

Larvae: 3 live worms per 100 terminals or 3% damage to squares, blooms, bolls

Currently, we have experienced no unexpected injury to Widestrike III or TwinLink technologies. I would not assume these varieties to be bulletproof in a high pressure year, but I do think that these technologies offer good protection in our area.

I recommend spending the extra money on a worm-specific product instead of relying on pyrethroids. Vial tests in Suffolk have indicated a trend towards resistance for several years and there have been field failures reported south of us this season. Besiege and Prevathon are good choices because they offer residual control. Besiege targets sucking-bug pests in addition to worms. I have had inquiries about Intrepid Edge. Virginia Tech has not tested this product in cotton. It has performed well in soybean tests and in cotton tests in other regions (Jeremy Greene- Clemson University, South Carolina). Keep in mind that no product works well against large larvae. Due to the early nature of this year’s flight, we may experience additional pressure later this season. I will keep you updated on what’s happening in Virginia. Please call if you have anything to report.

Sally 919-801-5366