Cabbage Insect Update

Bill Hutchison and Eric Burkness, Department of Entomolgy, University of Minnesota

This past we observed a significant increase in cabbage looper and imported cabbageworm egg-lay in the Apple Valley area (southeast of the Twin Cities). Infestations ranged from 30-40% of the plants infested, with eggs and/or early instars. As indicated in previous issues, control should be initiated when infestations for a given pest reach the following action thresholds.

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

Re: Cabbage Aphids! Some fields have had high infestations in recent weeks, and we have had some questions about the presence of aphid "mummies" (i.e., brown, hard-shelled aphid shaped forms sticking to the plant surface). The good news is that these aphids have been killed by a parasitic wasp; the bad news is that high numbers of the mummies on the plants MAY be a "contaminant" concern for some growers (markets). Hopefully, most of these will be on the lower leaves, and can therefore be avoided when cabbage heads are harvested. If aphids are building up, and the crop is approaching harvest, and there does not appear to be enough naturally occurring biological control (lady beetles, parasites, lacewing larvae, etc.), then a one-time application of a non-pyrethroid insecticide (e.g., Metasystox-R, Dimethoate, Provado), may be needed. Check the label and pre-harvest interval restriction.

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Mummified aphids caused by a parasitic wasp

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 August 16, 2000.
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