Vegetable Scouting Report: June 4, 2025

All/multiple crops: Swings in weather continue to cause issues across crops. Wind-whip, which occurs when young plants are twisted and the stems are damaged, has been widespread in seedlings not protected by row covers, and tender transplants such as cucurbits have experienced some cold damage. Crops may continue to exhibit stress symptoms into this upcoming warm period. Do not over-fertilize to compensate; this may damage plants more than help. Fertilizer when growth resumes.

Alliums: Thrips have been observed over threshold (one thrips per leaf on average) on overwintering onions and shallots. Conventional growers can use this flow chart to choose insecticides. The most effective organic product is Entrust (spinosad) mixed with an adjuvant to improve coverage.

Brassicas: Flea Beetle pressure is increasing; pay close attention to young plants which are most susceptible to damage.

The first Swede Midge of the season was captured in Essex County last week. Emergence appears to be slightly delayed compared to previous seasons due to cooler temperatures. On farms with known swede midge populations, new brassica transplants should be treated with a systemic insecticide (e.g. Assail or Admire Pro) or immediately covered with netting. Crop rotation away from fields with infested crops the previous year is critical to managing populations.

Cucurbits:  Striped cucumber beetles have now been observed across the ENY region. Regular scouting is critical to managing striped cucumber beetle and bacterial wilt. When cucurbits are at the cotyledon to four-leaf stage, treat if more than 5 beetles per plant. For older plants (four-leaf stage and above), crops susceptible to bacterial wilt (e.g. cucumbers) should be treated when there is at least one beetle per plant on average.

Nightshades:  Lots of tomatoes, peppers and eggplant are going in the ground this week with the break in weather.  With the heat predicted for the next couple of days, make sure if you are using plastic mulches, that the beds are properly filled in so there are no gaps between the plastic and the mulch.  Planting a any transplant in a poorly filled bed will lead to issues like burn off where the plant is planted deep and has a greater chance of touches the sides of the plastic.  This causes a girdling of the stem and eventual death of the transplant.  Make sure beds are also moist, especially with bright sunny days and 80–90-degree days predicted.  Those transplants that were set out prior to the rain last week are looking a bit rough – cold and wind damage have left their marks on the plants like poor color, whitening of some of the leaves, bent or broken stems etc.

Sweet corn:  Now that floating rowcovers are coming off across the region, there are no surprises as to what’s underneath……weeds and more weeds!  Controlling them now is critical as bigger weeds are harder to control and the fewer herbicides we also have labeled for later stage corn growth.  One of the effective products that works well on most broadleaves and annual grasses is called Armezon (topramezone).  However, you need to add all of the correct additives including methylated seed oil (MSO), atrazine and a nitrogen product (UAN, AMS etc.).   Other options as well as rates and adjuvants recommended to be used with the products can be found in the Sweet Corn Post Emergent Herbicide Table along with some other comments.  In the meantime, keep these things in mind when considering your choices:

• Know what weed species you are going after – some of these herbicides have a very narrow range of weeds they control as well as certain size weeds.
• READ THE LABELS and make sure you choose the right adjuvants and other additives such as nitrogen products to get the optimal control while ensuring crop safety
• There are many generic formulations out there so be sure to check the labels and know what you have – the tables in the links are only a few suggestions to help you and is not a complete list.

Miscellaneous:  Weed Control between Plastic Mulches:  With the warming conditions and lots of plastic mulchers being laid this week, controlling weeds between the rows of plastic is critical.  The first thing is DO NOT APPLY ANY HERBICIDES BROADCAST OVER THE TOP OF THE MULCHES BEFORE PLANTING!!!!!  You are taking a huge risk that even after a couple of rains that the herbicide may remain on the plastic and could concentrate in the planting hole after you’ve planted with a rain – especially in cases where beds are not uniformly full and you have dips in your beds where water can gather on the plastic.  For the optimum crop safety, apply the herbicides between the beds, just letting the spray contact the shoulders of the bed using very directed sprays or a shielded sprayer, with air induction nozzles at very low pressure on calm days or evenings to reduce the drift potential onto the plastic or crop.

If the material is labeled on the crop, then it can be used in the row middles too unless otherwise specified on the label that it cannot be used between the rows.  The table below has a listing of herbicides and the crops they are labeled for. Using a pre-emergent or combination of pre-emergents before transplanting is the best strategy as to minimize the risk of drift and hitting your crop.  Herbicides Labeled for Between Rows (row middles) of Plastic Mulches on Various Vegetable Crops:

*Dual Magnum and Reflex are 24C Special Local Needs Labels and require specific “Indemnified” labels through Syngenta in order to use them on these crops.  To register go to: https://www.syngenta-us.com/labels/indemnified-label-login and follow the directions.  This needs to be done every year in order to use these materials on these crops.

This is not a complete list of herbicides labeled for use between rows of plastic mulch. Do not use this list in place of the product label as in some instances a product may be labeled on some but not all crops in the same family.  For example the term “brassicas”, includes cabbage, broccoli and many crops leafy brassicas such as kale.  However, these products may not be labeled on all members of the brassica family so please read the label before using.

For organic growers, good results can be achieved with mulching using straw or some type of hay mulch or a permeable landscape fabric or weed mat pinned to the sides of the beds.  Careful, shallow cultivation with a Hillside or Lilliston Cultivator or a combination of S-tines and spyder cultivators and can also be fairly effective in controlling weeds between the beds of plastic.  Although tricky, the use of a shielded flame weeder for row centers could also be considered.

Contributors: Cornell Cooperative Extension Specialists Chuck Bornt, Teresa Rusinek, Ethan Grundberg, Elisabeth Hodgdon and Crystal Stewart-Courtens.