David Owens, Extension Entomologist, owensd@udel.edu
Asparagus
Asparagus beetles don’t typically start coming out until a little bit later, but with the warm winter they may be active earlier than usual.
Cole Crops
Cabbages are going in and now while they and other brassica transplants are small is an extremely important time to scout for flea beetles. They are small, dark beetles that jump. In cool weather when plant growth slows down, they can cause significant defoliation. Thresholds are very low at the cotyledon stage, afterwards they are 1 beetle per transplant. 10-20% defoliation can significantly reduce yield.
Almost all of the important brassica pests are active; this includes harlequin bugs and most of the ‘worm’ complex. Thresholds are 20% plants infested during the seedling stage, and 30% infestation until cupping. It is best to hold off using pyrethroids until the end of the season, this way beneficial insect activity is preserved. Labeled insecticides can be found in the Commercial Vegetable Production Recommendation Guide: https://www.udel.edu/academics/colleges/canr/cooperative-extension/sustainable-production/commercial-crops/vegetable-crops/midatlantic-vegetable-recommendations/.
Seedcorn Maggot
The seedcorn maggot trial at Georgetown has been very successful so far. Maggots that were developing from a field with cover crop tilled in and manure applied 4 weeks ago are pupating. First generation adults will be active from this planting in about a week or two. If you are tilling in cover crop or have recent manure application, you can expect seedcorn maggot activity to some degree or another for 3 weeks after.