Vegetable Crop Insect Scouting

David Owens, Extension Entomologist; owensd@udel.edu

Tomato
Corn earworm management was discussed in a post by UMD earlier this week and can be found here: https://extension.umd.edu/sites/extension.umd.edu/files/_docs/VegetableFruitNews10-5.pdf. This from Kelly Hamby et al. (UMD): Eggs can be detected on the leaves directly below the flower clusters, typically on the highest clusters on the plant. For a reduced spray approach, inspect 20-30 plants for signs of eggs, and consider initiating sprays if ~10% of the plants have at least 1 egg, with subsequent sprays at 3 damaged fruit per 100 unripe (Kuhar et al. 2006). Given the number of insect pests (armyworms, hornworms, stinkbugs, etc.) that occur in tomatoes, a 7 to 10-day interval once fruit begins to set is often used for insect management. Pyrethroids (Group 3A) offer poor to moderate control of corn earworm in the Mid-Atlantic, and will not control heavy infestations or large worms. In addition to the products mentioned above, several other effective insecticide options are labeled for tomato, including Avaunt (Group 22), Proclaim (Group 6), Rimon (Group 15), and Exirel (Group 28). It is important to rotate insecticide classes within a season. ALWAYS read pesticide labels carefully and follow all instructions; the information presented here does not substitute for label instructions.

Beans
Continue scouting for corn earworm. Moths are present in fields and are attracted to blossoms to feed. Pyrethroids alone may not provide adequate control. Something of interest, our blacklight traps do not often capture more than a handful of moths per night even though pheromone traps indicate potentially large populations active in the region. Thresholds for lima beans are 1 per 6 row ft. Non-pyrethroid control options include Lannate, Blackhawk and Radiant, Intrepid, and Coragen.

Sweet Corn
Corn earworm management in vegetables was recently discussed in a UMD article that went out earlier this week and can be found here: https://extension.umd.edu/sites/extension.umd.edu/files/_docs/VegetableFruitNews10-5.pdf

Moth captures remain quite high. Vial testing results indicate that 50% of moths are surviving pyrethroid challenge. Pyrethroids used ALONE may require shorter spray intervals, especially during the first week of silk. If using Lannate, use the higher rates. Besiege or Coragen both have chlorantraniliprole in them, this active ingredient is very good against moths and these products should be in the rotation, especially earlier in the silking period when moth activity is greatest. They are both translaminar products, especially helpful when wet weather is forecast.

Moth trap captures are uploaded to our website by Tuesday and Friday. Thresholds and trap captures can be found here: http://extension.udel.edu/ag/insect-management/insect-trapping-program/. Trap captures from Thursday are as follows: