University of Delaware IPM Program Joanne Whalen - Extension IPM Specialist
1. General Scouting Pattern: 5 consecutive plants in 10 locations for up to 50 acres; add one additional sampling location for every 10 acres of land; V- shape should be used to cover entire field
2. Before Heading: Be sure to check for insects feeding deep in the whorl
Pest
When to Sample
Action Threshold
Thrips
Spring Planted; From transplanting/plant emergence to harvest
20 % plants infested - treat before thrips move deep into wrapper leaves
Aphids
Generally Spring Planted; Seedling Stage Plants
Rarely a problem in our area; 10 % of the plants with one or more colonies per plant
Imported Cabbageworm
Spring Planted Cabbage; Seedling Stage to Harvest; overwinters in the Mid-Atlantic
Pre-Heading: 20% plants infested
Heading to Harvest: 5% plants infested
Cabbage looper
Generally a pest of fall planted cabbage; migratory pest; Can attack spring planted fields in June if migrates early to our area
Pre-Heading: 20% plants infested
Heading to Harvest: 5% plants infested
Diamondback moth larva
Spring and Fall Planted Fields; Significant problem with fall plantings; overwinters in the Mid-Atlantic
Feeding in the heart preheading: 5 % infested
Feeding on wrapper leaves preheading: 20% infested plants
