Vegetable Scouting Report: August 13, 2025

All/multiple crops:

Dry conditions continue throughout much of our region, particularly in the Lake Champlain Valley. Keeping crops irrigated through the heat wave has been a priority for many farms over the past week. As we are now in peak harvest season, our vegetable scouting reports may be lighter than in previous weeks as many pests and diseases are now “old news.”

Are you noticing poor residual herbicide activity recently? The dry weather may be to blame, according to Dr. Lynn Sosnoskie, Assistant Professor of Weed Ecology and Management at Cornell:

“Soil moisture matters: Dry surface soils at application need more rainfall for activation than moist soils. So, even if you did get rain, it may still not be enough for proper incorporation.

Use of higher labeled rates (if crop safety won’t be compromised) may help reduce variability from limited rain or soil moisture. But dry soils will see less microbial activity, so carryover may be a concern the following season.

No rain after application and weeds are getting up? Use a rotary hoe or harrow to control weeds before they emerge (white root stage). If mechanical control isn’t possible, begin scouting to time postemergence applications.

Pay attention to post-activation weather: Even after receiving sufficient rainfall, prolonged dry conditions can reduce control as herbicides bind to soil particles.

Herbicides less tightly bound to soil colloids may give more consistent results in dry years. Always pay attention to rotation restrictions and remember the previous point about carryover.”

Alliums:

The third flight of leek moth continues in the north this week. See previous alerts for more information on IPM for this pest.

Onion harvest continues in the region. See Cornell Vegetable Specialist Christy Hoepting’s tips for harvesting, drying, and curing onions here.

 Brassicas:

Dewy nights are leading to peak alternaria weather in fall brassicas. See this table for effective fungicide recommendations.

Swede midge damage symptoms are becoming increasingly evident on farms this month, as populations build over the season. Timely crop destruction after harvest is especially important in a swede midge IPM program. Broccoli that sends out multiple shoots after harvest is an excellent host for swede midge, and populations that build in previous crops can then move to fall brassicas. Rotation away from earlier infested brassica plantings, use of insect exclusion netting, and insecticide treatments are key to preventing swede midge damage in fall plantings. Remember that netting is only effective if not used over ground with swede midge pupae (i.e. ground that has not had infested brassicas for at least 2 years).

Cucurbits:

Cucurbit downy mildew is making its way north, slowly thanks to the dry weather. Downy mildew was identified this week in Essex County. More cucumbers were also diagnosed with CDM in Albany and Columbia Counties late last week and early this week. Continue to apply protectant and CDM specific products such as Ranman, Orondis Ultra, and Zampro.  Powdery Mildew is also starting to show up, especially in older plantings of summer squash that is no longer being harvested. Whenever possible, when these plantings are finished, mow or burndown with non-selective contact herbicides like paraquat or gramoxone to help reduce the amount of inoculum that can infect surrounding plantings.

There are a lot of pumpkin and other fall ornamental fields that are showing a lot of yellowing in the foliage and most of this is being caused by the hot, dry conditions we continue to experience this season. If you can, a quick watering certainly wouldn’t hurt if you have the ability to do so. Not only will sparse or weak foliage affect fruit size, but also increase the chance of sunscald.

Nightshades:

Anthracnose (Colletotrichum) on peppers and tomatoes is showing up, particularly in plantings with over-ripe fruit. This disease causes water-soaked circular lesions that turn salmon colored before being engulfed in black spores. Fruit with lesions should be discarded, as symptoms will advance in storage and may spread. Remove diseased fruit from the planting if possible to reduce inoculum. There are targeted chemical control options including Aprovia Top, Inspire Super, and Cabrio. Mix all of these with a protectant fungicide, and remember that chlorothalonil is not labeled for use in greenhouses and tunnels. Organic and tunnel growers may use copper as a preventative fungicide. For more information including pictures, see this article.

As of this week, we have not observed late blight in tomatoes or potatoes in Eastern NY.

Sweet corn:

The good news this week is that corn earworm moth numbers seem to be trending downward in most of the region with the exception of a couple sites. The bad news is that western bean cutworm moths continue to be caught at many of the sites. As mentioned the last couple of weeks, WBC likes younger corn, especially that which is about to tassel soon.  The best opportunity to control the larvae is when they hatch and ride out of the whorl on the tassel. Treatments that work for CEW will also control WBC. Currently there haven’t been any signs of northern corn leaf blight or rust so far this season, but once the cooler nights start and the dews get heavier it won’t be long for it so show up!

Miscellaneous:

Basil downy mildew has been reported in Eastern NY and in Massachusetts. Long Island researchers have found that a rotation of Ranman with K-Phite, Presidio with K-Phite, and Orondis Ultra was effective to manage basil downy mildew conventionally, while Stargus, LifeGard, Eco-Swing, and Regalia, with copper products, provided fair control if applied frequently and with coverage of undersides of leaves. If you have basil downy mildew on your farm, please let us know so that we may send samples to Rutgers University researchers studying the disease.