Vegetable Crop Insect Scouting

David Owens, Extension Entomologist, owensd@udel.edu

Cucurbits
Continue scouting for squash bugs and aphids in fields treated earlier for squash bug or squash vine borer. Check under leaves for egg masses or for young nymphs. Treatment thresholds are one egg mass per plant, and to wait to spray until eggs hatch. Of course, if you see an egg mass’ worth of nymphs running around, you may want to spray them.

Lima Beans
Scout for soybean looper. Unlike in soybean, loopers will eat small lima bean pods in addition to foliage. Corn earworm may also be present in fields. Moth counts have been high recently and the most attractive places for moths to visit now are fields with flowers. Pyrethroids will not provide adequate control of either species. Lannate, Radiant, Avaunt eVo, Intrepid and diamide containing products such as Coragen, Exirel, and Besiege should do well against earworms. Diamides though can be less consistent with loopers. The earworm threshold is 1 larvae per 6 row ft. Soybean looper probably should be included in this threshold as well.

Sweet Corn
Moth counts are very high. We have completed our vial bioassays for 2020. Most recently, we have tested 55 moths and have had 35% survive cypermethrin. You should not rely on pyrethroids alone in a spray program. At some point next week, temperatures are forecast to dip below 82 degrees, meaning it would take eggs 3 days to hatch. Spray schedules should be tightened a day when temperatures are above this mark and can be a ‘normal schedule’ when temperatures cool.

Thursday trap capture is as follows: