David Owens, Extension Entomologist, owensd@udel.edu
Cole Crops
Scout cole crops for worms. Right now, imported cabbageworm is the most active of the worm complex. Thresholds are based on plant growth stage. During the seedling and early transplant stage, treat when 20% of plants are infested. Prior to cupping or early head initiation, thresholds are 30%. Adjuvants to help spread droplets and stick them to the waxy cuticle will help improve coverage and efficacy.
Greenhouses
Scouting greenhouses this week so far has only turned up isolated aphids. Check flats close to the air intake vents. Some plants had enough aphids on them to cause leaf curling.
Seedcorn Maggot
First-generation seedcorn maggot flies peak emergence will be occurring this week coming. This next flight is usually the last one to potentially cause significant injury. I am starting to see flies again in my maggot field, with many pupae still developing. Fields at risk will have just had a cover crop or manure tilled into the soil. In such fields, the use of seed treatment is strongly advised.