While presenting at a community garden meeting with growers and gardeners in Boydton, VA this morning (Sept 10), one of them talked about a pest that was creating holes in her sour gherkin cucumbers. I checked it out and it was pickleworm (see photos). Location was Clarksville, VA. This is not good news for our large pumpkin industry in Virginia. This means that at least some of these tropical moths have mead their way from the southern U.S. on storm fronts and are depositing eggs on blossoms of cucurbit host plants like cucumbers, squash, and pumpkins.
Pickleworm holes in gherkin cucumbers – Clarksville, VA September 10, 2025. Pickleworm larva crawling out of infested cucumber.
Larvae bore into fruit where they can cause the fruit to rot in addition to reducing marketability of the fruit. Growers should inspect their fruit and blossoms regularly until harvest. If pickleworm is found, there are many effective insecticides to control it, but the most affordable would probably be a pyrethroid.
Like every year, I get a lot of questions on late leaf spot fungicides the closer we get to digging. Since it’s near the end of the season, regardless if you’ve been on a rigorous, effective leaf spot program you’re going to see some leaf spot. I’ve heard some growers are having severe leaf spot and some significant defoliation. Below I’ll cover some points regarding late leaf spot management as we approach digging.
Leaf spot has a greater affect on yield the earlier it occurs. If the onset of disease begins near harvest we often don’t observe much loss. I’d be more concerned about yield loss in fields where leaf spot was significantly spreading in early to mid-August compared to just seeing it get worse since labor day weekend. However, if you see up to 40% or more defoliation, a fungicide application at that point isn’t going to help and you may consider digging early to help preserve yield.
The cooler it gets leaf spot takes longer to spread. Cooler weather coupled with the extremely dry weather we’re experiencing really slows disease development. The big increases in leaf spot you’re seeing now are the result of infections that took place 2-3 weeks ago or more. That would mean the fungicide applications you made (or not) early to mid-August are impacting what you’re seeing now more than sprays you applied within the past 2 weeks. Applying a fungicide now won’t have a major impact on leaf spot or yield.
Just because I just said spraying leaf spot now won’t have a big effect on yield doesn’t mean spraying for leaf spot is a terrible idea right now. A lot of that depends on how close you are to digging based on peanut maturity. If you’re over 2 weeks away from digging I can see where a fungicide application may help leaves stay on longer and prevent yield loss compared to peanuts that are within 2-weeks of digging. Everyone’s maturity situation is different, and it can vary from field to field. The situation is very different between dryland and irrigated peanuts. In talking to Jacob Forehand in Virginia and David Jordan in NC this morning, according to pod blasting results, peanuts are not maturing very quickly due to cool, dry conditions and peanuts may be mature a little later than “normal”. Plus, although the forecast isn’t calling for much rain, if it becomes warmer and we get some unexpected rain that can change things so far as maturity and diseases are concerned. Lots to consider…
If you’re going to use a fungicide this late, make sure it’s a fungicide that’s going to be effective (kinda intuitive I know). I hear about a lot of people making fungicide recommendations that are questionable. If you ask me about a fungicide to use right now I’m going to tell you to use Provost Silver or chlorothalonil (Bravo, Echo, Equus etc) with or without micronized sulfur. Why those? They are the only fungicides that I am confident in providing some control. The efficacy and curative activity of Provost Silver is well established, chlorothalonil works as well as it did when it was first used back in the 70’s because it has multiple modes of action and carries practically no risk of resistance development, and micronized sulfur has been shown by several researchers in several states to enhance the efficacy of leaf spot applications when mixed with an effective fungicide. Each product has some downsides which may be a cause for pause.
We use FRAC Group 3 fungicides in almost every application we make on peanuts, and the actives in Provost Silver are both groups 3’s. Provost Silver is probably the most used FRAC Group 3 fungicide. The more we use the same MOA (mode of action) over and over again we put more pressure on them for resistance development. Couple that with spraying when higher inoculum levels are present during the late season adds more to the resistance risk.
Chlorothalonil has been shown to increase the risk of spider mite development, and to a lesser degree it can enhance the development of Sclerotinia blight. As dry as it is I can see growers being resistant to use chlorothalonil because of spider mites. But since sulfur has some activity against spider mites, I’ve been suggesting tank-mixing it with chlorothalonil to provide some control of spider mites. Spider mites are favored by hot, dry conditions. We have the “dry” but don’t have the “hot” right now and looking forward. I’m not saying there’s no risk of spider mite infestations right now, but conditions are less favorable for them to occur.
The main issue with sulfur are problems with mixing and it’s potential to leave residues in spraying equipment that can cause clogging. I recommend trying different formulations of micronized sulfur. The one’s I’m familiar with are Microthiol Disperss® (dry), Kolla® (liquid), and Suffa® (liquid). I keep using the word “micronized” for a reason. That is that all the positive efficacy data I talked about earlier was with micronized formulations only. Non-micronized sulfur does not show the same positive effects on leaf spot control.
Corn earworm larvae have been found well in excess of economic thresholds in several counties throughout Virginia the past two weeks. In Prince George, we sampled a field with 50+ larvae per 15 sweeps (see below photo). There are a few key things to remember for managing corn earworm in soybeans.
It pays to scout. Use the economic threshold. For corn earworm in soybeans, we have what’s called a “dynamic threshold”. The benefit of using a dynamic threshold is that it shifts with commodity prices, production practices, and the cost of control and you can be certain that you will get economic return on a spray under current conditions. You can find the calculator here. At an estimated soybean price of $10/bu, and $15 cost of control using a sweep net to sample 15 inch soybean rows you get an economic threhsold of 2.2 larvae per 15 sweeps.
We have expanded our corn earworm moth monitoring in 2025. While these traps do not indicate the need to spray alone, they can guide your scouting efforts and help make decisions. The monitoring tool is updated in real time and can be found here.
Select the right insecticide Pyrethroids alone will have limited efficacy for corn earworm, particularly for large larvae. Our most recent efficacy data can be found in the figure below. These numbers are total number of corn earworm larvae per 15 sweeps at 2 days post application. If targeting stink bugs as well as corn earworm a product containing both a pyrethroid and a diamide (I.e. Besiege or Elevest) would be a good option. If you are also reaching defoliation thresholds (15% during reproductive stages) and have mostly soybean loopers, Besiege has offered limited control for soybean loopers in recent years. Intrepid Edge or Steward are good options to manage both corn earworm and soybean loopers.
As always, please contact me if you have any questions or concerns. Tim Bryant (btim2@vt.edu).
Pheromone trap data from our cooperators across Virginia are in this Table. Virginia Cooperative Extension Agents Hélène Doughty (Northampton County) and Scott Reiter (Prince George County) reported many corn earworm larvae in soybean fields this week. Scott’s black light trap averaged 9.3 moths per night. With his help, our entomology program put in an insecticide efficacy experiment in Prince George soybean on August 20. The economic threshold calculator for corn earworm larvae in soybean can be found here. Our cypermethrin adult vial tests show 46% dead or down moths after 24 hours exposure time to this pyrethroid insecticide (n = 594 moths tested this season).
Updated corn earworm moth catches from our pheromone trap network are in this Table. Prince George County’s black light had 11 total moths over the past 8 nights, but high numbers were caught in that county’s pheromone trap (averaging 42.5 per night over the past 8 nights).
Today in a project supported by USDA-NIFA Crop Protection and Pest Management’s Extension Implementation Program, our entomology crew sampled cotton in Suffolk, VA with no genetic protection against bollworm and found 14% boll injury due to this pest in the insecticide-untreated plot. There was no boll injury due to bollworm in the insecticide-untreated WideStrike or Bollgard 3 plots.
Recently, soybean aphids have been confirmed at higher populations than typically expected in August. While many folks are scouting for worms and stinkbugs, we also recommend looking for aphids in your soybean fields as well. The key variables to consider regarding managing soybean aphids are the number of aphids per plant and the soybean growth stage. Information from our Pest Management Guide on Soybean Aphids in summary including info on thresholds and sampling are as follows (VCE Field Crops PMG, Publication 456-016):
Number of aphids per soybean plant
The current economic threshold for aphids is an average of 250 aphids per plant, on two consecutive field visits spaced about 5-7 days apart. This is because aphid populations can “crash” quickly due to heavy pressure by natural enemies like lady beetles, parasitic wasps, and fungal diseases. When scouting, choose a “Z” or “W” shaped pattern to cover the entire field and sample at least 20 to 30 plants per field by examining the entire plant, including stems and upper and lower leaf surfaces. Use the aphid/plant average for determining the need for treatment.
The soybean growth stage
The threshold of 250 aphids per plant applies to soybeans through the R5 growth stage (3 mm long seed in the pod at one of the four uppermost nodes on the main stem), after which time plants can tolerate 1,000+ aphids with no threat to yield. If an insecticide is applied for aphids, pyrethroids (e.g. bifenthrin, Warrior II, Mustang Max, etc.) can be effective for management, but choosing a more selective insecticide can preserve natural enemy populations and limit future flare ups of aphids or other pests.
The August 2025 corn earworm moth pheromone trap data (to date) can be found in Table 3. Some of the higher catches occurred in Brunswick, Prince George, and Rockbridge, VA. Last month’s data can be found in Table 2. Scott Reiter’s black light trap in Disputanta captured a total of 30 moths this week (6 nights).
We’ve evaluated 470 moths in our cypermethrin vial tests, with 48% dead/down after a 24-hour exposure to this pyrethroid insecticide at the 5 microgram/vial rate.
With as hot as it’s been in July, it’s hard to imagine Sclerotinia blight showing up in peanuts. I have been searching for it in my trials but haven’t seen it yet. However, highs in the low 80s and lows around 70 today through next week means conditions will be favorable for disease development. Plus, adequate soil moisture is present due to recent rains and peanut canopies are dense enough to favor Sclerotinia blight. I recommend monitoring the Virginia Sclerotinia Blight Advisory on the Peanut Cotton InfoNet to check the risk of this disease in your area and scout for disease, especially in fields with a history of Sclerotinia blight. Access the Peanut Cotton InfoNet using this link https://infonet.ext.vt.edu/. You can also call the VA Peanut Hotline at 1-800-795-0700 for up-to-date disease advisories.
At this point in the season I recommend fungicides Omega or Vantana tank-mixed with a leaf spot fungicide if you haven’t already applied Miravis + Elatus. I hesitate to recommend the first application of Miravis + Elatus this late in the season due to concerns about late leaf spot escapes as these products have no curative activity against leaf spot. You’re okay if it’s the second application. Fontelis at 1.5 pt/acre can provide some disease suppression if sprayed preventively.
Please contact me if you have questions.
David Langston. (757) 870-0498 cell email: dblangston@vt.edu
Pheromone trap catches of corn earworm (=bollworm) moths are available in this Table. The Prince George black light trap averaged approximately 13 moths per night this week and that county also had high pheromone trap catches. A peanut field at the Tidewater Agricultural Research and Extension Center in Suffolk, VA hit corn earworm larval threshold numbers (8 larvae per drop cloth sample) and we dropped in an insecticide efficacy experiment. We were finding 2.5 bollworm eggs per 100 cotton terminals this week in Suffolk. Our cypermethrin adult vials tests indicate 44% dead or dying moths after a 24-hour exposure to this pyrethroid insecticide (n = 340 moths tested from Suffolk).
Corn earworm moth pheromone trap catches started to increase this week in some counties where captures have previously been low. The highest nightly averages were Brunswick (47), Prince George (30), Accomack (20), Greensville (15), Virginia Beach (13), and Southampton (11). Here is the Table. Black light trap catches at Prince George (Disputanta) averaged 3 per night. Cypermethrin vial test results are 53% dead or down moths after a 24-hour exposure to this pyrethroid insecticide at the rate of 5 micrograms per vial (n=178 moths tested). I found a bollworm egg in cotton on July 23 in Suffolk, VA.
