Cabbage Insect Pest Update

Eric Burkness, Dept. of Entomology, University of Minnesota, St. Paul, Minn.

Cabbage looper (CL) and Imported cabbageworm (ICW) infestations remain low. Cabbage looper pheromone trap catch has remained below 1 moth/trap/night. Cabbage looper eggs are being laid and hatching with a per plant infestation level under 5%. Egg lay and larval infestations can be expected to continue to increase. Fields should be monitored 1-2 times/week to determine infestation levels of CL, ICW, and DBM. Diamondback moth larval infestations are at 10-20%. However, parasitized diamondback pupae have been found and parasitism rates can reach up to 90%, which should hold populations under threshold. Treatment decisions should be based on current thresholds for a given pest. Thresholds are based on the pest and plant growth stage. The following thresholds have worked well in recent IPM implementation studies at Rosemount and Apple Valley, MN with Pahl’s Farms.

Plant Growth Stage	%Plants Infested	Pest Complex
Vegetative (pre-cupping)	10	CL
	30	ICW and/or DBM
Cupping/Head to Harvest	10	CL, ICW, and/or DBM

Co-Editors: Bill Hutchison, Department of Entomology, University of Minnesota, hutch002@tc.umn.edu
Jeanne Ciborowski, IPM Program, Minnesota Department of Agriculture, jeanne.ciborowski@state.mn.us
Cindy Tong, Department of Horticulture, University of Minnesota, ctong@extension.umn.edu
Production Editor: Suzanne Wold, Research Specialist, University of Minnesota, woldx018@tc.umn.edu

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Last Revised July 27, 2000.
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