David Owens, Extension Entomologist, owensd@udel.edu
Seedcorn Maggot
Our predicted peak Seedcorn maggot fly emergence occurred this past week. Flies are attracted to fields with heavy organic matter incorporation, especially manure tilled in. The ideal conditions for Seedcorn maggot (SCM) are wet soil, heavy organic matter incorporation, field planting within about 5-7 days, followed by cold weather that slows seedling emergence. With the loss of chlorpyrifos and the effective loss of Diazinon, we are reliant on neonicotinoid seed treatments for SCM control. A question came in recently if a field is worked about 3 weeks before planting, and then lightly disced ahead of the planter, would it still face high maggot pressure? It’s certainly a good question to do some research on. I would think the pressure would be much reduced. Three weeks should allow SCM to complete larval development but not have enough time to complete total development or adult maturity.
Greenhouses
Make sure that greenhouses are weed free. We do not want to be harboring an early population of spider mites that might then infest spring transplants.