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.

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.

1. 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.
2. 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.
3. 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…
4. 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. 
5. 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. 
6. 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.
7. 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.

1. 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.
2. 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).

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

We hit the tarnished plant bug threshold for the first time this season on July 15 at the Tidewater AREC, in Suffolk. Reports of threshold numbers are rolling in from collaborators as well. Here are a few key reminders for successful plant bug management this year;

1. Use economic thresholds

These economic thresholds are the point at which you will see a return on investment from spraying for plant bugs.

Pre-bloom threshold;

8 plant bugs/100 sweeps AND less than 80% square retention

Many of our cotton fields here on the research farm and in on-farm trials are beginning to flower this week. Once you reach 50% of plants in a field with flowers, switch to using a drop cloth to sample plant bugs. The drop cloth should be placed on the ground between two rows and the plants on either side vigorously beaten over top of the sheet. Take a sample in 6-8 spots throughout a field and average to determine the number of bugs per drop cloth sample. Making the switch from sweep net samples to drop cloth samples during bloom is critical for making informed management decisions on plant bugs.

Threshold from the 1^st week of bloom on;

3 plant bugs/5 row feet

Even if you are using a Thryvon cotton variety, it still needs to be scouted and treated for plant bugs at the recommended thresholds. Weekly scouting will provide the best insight on when and where insecticide applications are needed.

2. Insecticide rotation

Hold off on using strong broad-spectrum insecticides until late in the season. These include pyrethroids and organophosphates;

Organophosphates: Bidrin, Orthene

Pyrethroids: Warrior II, Bifenthrin, countless generics (look for insecticide MOA 3A on the label). Many premixed products, including Endigo or Brigadier include a pyrethroid.

Plant bugs have developed resistance to pyrethroids, and these products eliminate beneficial insects, which may keep other pests in check later in the season. An early pyrethroid spray can often flare spider mites, aphids, and bollworms later in the year.

A good option for your first spray for plant bugs is Transform @ 2 oz/ac. Diamond @ 4-6 oz/ac can be included as well, where there are nymphs present. This product is an insect growth regulator and will not have activity for adult plant bugs. If timed correctly, it has been shown to increase the time before another plant bug spray is needed. Neonicotinoids (Centric, Admire) can also be effective early in the season, but need to be combined with other products to get good control as the year progresses. Be sure to check the label for restrictions on use patterns during bloom (e.g., application restrictions because of risk to bees and other insect pollinators).

David Langston 07/09/2025

Peanuts are growing fast and that first leaf spot spray has been applied or should be soon.  Typically folks go with Bravo (1.5 pt), Alto + 1.0 pt Bravo, or Aproach Prima + 1.0 pt Bravo with or without tebuconazole.  With the weekly rain and high humidity, conditions for leaf spot are favorable.  Some folks are thinking about their second spray pretty soon.  Fungicides I like for the second spray are Provysol + tebuconazole, Lucento, Fontelis (1.0 pt) or Miravis.  If you have fields with a history of southern stem rot (white mold) you may need to tank mix the leaf spot fungicide with Convoy, Elatus or Excalia or bump the Fontelis rate up to 1.5 pts.  I’d plan on the third spray being Bravo at 1.5 pt + tebuconazole or substitute tebuconazole with one of the so. stem rot fungicides above.  The fourth spray I like Provost Silver because of it’s “kick-back”/curative activity.  The last spray or last two sprays can be either Provost Silver again or Bravo at 1.5 pt + tebuconazole.  If you think there may be issues with Sclerotinia blight, Omega/Vantana can be used, preferably at disease onset or before, or a second spray of Miravis + Elatus.  Don’t be afraid to use Bravo a couple of times as it doesn’t increase Sclerotinia blight unless it’s sprayed 4-5 times.  However, if it turns hot and dry you should avoid Bravo as it can flare spider mites.

Authors: Taylore Sydnor (Ph.D. Student), Alejandro Del-Pozo (Assistant Professor) & Thomas Kuhar (Professor) – Department of Entomology, Virginia Tech

Diamondback moth

Diamondback moth (DBM), Plutella xylostella, is an important pest of brassica crops worldwide including Virginia (Fig. 1). Management of this pest is challenging due to its ability to quickly develop resistance to insecticides. Therefore, integrated pest management (IPM) tactics are strongly desired. Mating disruption has been developed for DBM as an alternative to insecticides.  Mating disruption involves releasing high rates of the mating pheromone into fields confusing and/or desensitizing male moths so that they cannot find female moths and mate and produce damaging larvae on the crops.  The strategy has worked extremely well for tree fruit moth pests, and is currently being researched by our lab in Virginia for DBM. 

Mating Disruption Trials

In the past three years we have tested several mating disruption dispensers and other products in commercial cabbage and broccoli fields in Hillsville and Mechanicsville, Virginia.  Similar research has been conducted in North Carolina and South Carolina by our entomology colleagues.  Virtually all of our trials have resulted in sentinel trap shut down of DBM moth catch in the middles of commercial brassica fields that have had mating disruption pheromones released (via dispensers) as compared with non-mating disruption (control) fields that had significant moth catch in the fields (Fig. 2).  When male moths cannot find females, then there will be little to no DBM larval infestations on the crops.  The Trécé Incorporated dispensers (Fig. 3) used in the aforementioned research are not commercially available yet. 

Although we have tested various dispensers, tablets, and sprayable pheromones, with each demonstrating success for reducing DBM, the only commercial DBM mating disruption product currently available to growers is a sprayable pheromone, Checkmate® DBM-F (Fig. 4). The sprayable product has been around for a while, but not heavily used by commercial growers probably because of the plethora of effective lepidopteran insecticides that have hit the market in the past 25 years.  However, with DBM populations developing resistance to virtually all of the insecticide classes, mating disruption is now a more attractive option for managing this difficult pest. 

In 2024, we tested Checkmate® DBM-F in commercial cabbage in Hillsville, VA (4 treated fields paired with 4 control fields), then later in the fall in 2024 in broccoli in Mechanicsville, VA (1 treated field and 1 control field). 

Fields were sampled from July to August. Growers were encouraged to maintain their spray regimens to maintain homogeneity between field plots. All treatment fields in both locations were treated with Checkmate at a rate of 2 fl oz/acre approximately every 30 days. Three pheromone-baited delta sticky traps were placed equidistant in each field plot to monitor the DBM moth activity and were checked weekly. In Hillsville, we found that Checkmate® DBM-F was not significant in reducing DBM populations when compared to the control fields.  However, during this trial there was a lot of rain, 5.34” over a two-week span, that likely reduced the efficacy of the sprayable pheromone to last in the field. In fairness, the company does recommend re-applying the product after rain events.  See the following blog from Suterra that addresses the different rates and frequencies: https://www.suterra.com/blog/checkmate-dbm-f-flexible-spray-timings-for-diamondback-moth-control

This was not possible given the amount of rain that occurred during that 2-week stretch. We felt a more fair assessment of the product occurred with our test in Mechanicsville, where we found that DBM adult captures were significantly shut down in fields treated with Checkmate® DBM-F when compared to control plots (Fig. 5). Overall, we conclude that Checkmate® DBM-F has the potential to be effective in reducing DBM pest populations when applied at the proper conditions.  Growers need to be mindful of rainfall after application. 

Over the past three years, we have tested several types of mating disruption dispensers and products for DBM, and have consistently achieved sentinel trap shut-down (= effective control) of the pest in cabbage and broccoli fields in Virginia.  We encourage growers to try this innovative strategy for controlling this very difficult pest. Please feel free to contact us if you are interested in trying mating disruption for DBM in Virginia.   

Corn earworm is one of the most important pests of agricultural crops in Virginia feeding on corn, cotton, beans, tomatoes, and other crops. Often cold winters lead to high mortality of pupa in the soil and most CEW moths coming from more southern locations. Typically, we don’t see much moth activity and pest pressure until mid-July. But this spring we have seen some unusually high corn earworm moth activity at pheromone traps for this early in the year. Sweet corn grower Mr. Bill Tiver from Halifax Co. (near the North Carolina border) reported >30 moths in one night at his trap on May 26, 2025. Helene Doughty caught 50 moths at a trap in Northampton County this week. Delaware traps also are catching high numbers for late May based on recent correspondence from David Owens. This probably is the result of high overwintering survival of CEW pupa in Virginia or North Carolina soils and pupation already occurring. This could mean the start of a bad year for corn earworm, but so much of this depends on CEW moth flights rolling in from the South on prevailing winds during the summer. We shall see, but it would behoove you to monitor for CEW and keep tabs on this pest if you grow susceptible crops like sweet corn, soybeans, tomatoes, and others.