Vegetable Insect Update – May 4, 2018

David Owens, Extension Entomologist,

Cole Crops
Imported cabbageworm adults have been active for several weeks, and eggs and larvae can be found in fields. Other worms may start moving into brassicas, be sure to identify what you have. In general, seedling stage thresholds are 20% infested plants, 30% for early vegetative to cupping. Once cupping begins, thresholds for cabbage and Brussel sprouts plummets to 5% because we need to keep worms out of the harvested portions, and for other brassicas thresholds decrease to 15% and then 5%. Cole crop insect management recommendations can be found here:

Seedcorn Maggot
David Owens and Bill Cissel

Yesterday we finished digging up pea plants planted on April 3 immediately following a heavy application of manure. Although plants came up (slowly), we are just now seeing maggot damage, probably because early instar maggots were feeding on the organic matter before getting large enough to overcome our treatments. Maggots were late instar going into the pupae stage in Georgetown. With the warm weather, we will probably see second generation fly activity next week. Previous seedcorn maggot trials at UD have planted within 1 – 2 weeks of a manure application. If at all possible, plant a minimum of 3 weeks after working manure, compost, or a cover crop into the soil. If you do not have treated seed, are planting into a recent organic matter amendment, and are planting after mid-week, an in-furrow pyrethroid is your best management option.