Vegetable Crop Insect Scouting

David Owens, Extension Entomologist, owensd@udel.edu

Cucurbits
In the past week or so, cucumber beetles migrated in large numbers into a cantaloupe field at Carvel. This seems to be a bit unusually late. Most watermelon should be safe from defoliation at this time unless beetle feeding on young rinds is observed. Oblique banded leafroller has been reported in melons. Pay attention to this worm as fruit begins to grow, it can be an aggressive rind feeder. Aphids are colonizing melons and may be causing problems. Aphids spread numerous viruses besides the direct impact to the plants. Seed treatments will help protect pumpkins from aphids and from cucumber beetles for up to 3 weeks after emergence. This is long enough to protect from bacterial wilt. When scouting for aphids, look for shiny honeydew on the plastic and curled up leaves that may be covered in ants. There are multiple insecticides labeled for aphids, including materials active on worms and on beetles and those that are aphid specific. Squash vine borer is active. While it tends not to destroy many plants in large plantings, small plantings can be hit hard. Recommendations include pyrethroids or Coragen directed to the stems and base of the leaf petioles. Take care to scout such treated fields carefully as pyrethroid applications can flare up aphids several weeks later.

Solanaceous Crops
While recent rains are going to slow spider mite activity down, in vegetables, mites tend to persist through several days of rainy weather in part because we also are applying fungicides. Check eggplant for spider mite build up and consider a treatment when 4-8 mites per leaf are observed. Also scout for Colorado potato beetle in established plantings and flea beetles in young plantings.

Scout tomatoes for signs of mite feeding on upper canopy leaflets, particularly plantings carrying a fruit load. Scout also for signs of stink bug feeding on fruit. It will appear as discolored, cloudy areas on the skin of the tomato that will turn yellow when the rest of the tomato turns red. We do post stink bug counts on the UD insect trapping page from blacklight traps; so far this season our blacklights have caught a small fraction of what they did last year at this time.

Colorado potato beetle continues to be the main defoliator in potato. Potato leafhoppers are active in the area but have not been reported to be in any sort of significant number in commercial potato plantings yet.

Sweet Corn
Thursday trap captures are as follows: