Cole Crops Michigan
Coordinated by Zsofia Szendrei (, Associate Professor,
Entomology Department, Michigan State University


The economic value of crucifers (Brassicaceae) in the Midwestern United States exceeds $100 million annually; Michigan produces close to 110 million pounds of cabbage worth over $16 million annually (USDA-NASS, 2015) and is also a top producer of turnips and radishes (USDA-NASS, 2012). Cole crops are attacked annually by a range of insect pests and diseases, including a new invasive pest, the swede midge. Currently conventional management practices rely on weekly pesticide applications, even though thresholds are available for many of the cole crops pests.

Cole Crop
Cole crop. Source:Pixabay


This projects aims to survey Michigan cole crop fields in an effort to improve our understanding of current pest problems, share data with growers/crop scouts, and provide information on the prevalence and distribution of different pests. We will also train two undergraduate students on scouting and diagnostic methods. We will increase growers’ and crop scouts’ awareness of swede midges and other cole crop pests/beneficials and this will have a positive impact in terms of lowering pesticide use, reducing work exposure and reducing non-target impacts. We will increase knowledge and use of already available thresholds for caterpillar pests, and of the degree day model available for cabbage maggots. As part of this project we will produce a scouting guide that will contain the biology of all Michigan cole crop pests and available thresholds for insects and diseases.


The swede midge, Contarinia nasturtii (Kieffer) (Diptera: Cecidomyiidae), is a new invasive pest in Michigan; its presence was first confirmed in Michigan in 2015. After its first detection, Michigan cole crop growers have listed swede midge as one of the top priorities for research and extension in the state. In addition to swede midges, three species of caterpillars occur annually in conventionally and organically produced cole crops in Michigan: the diamondback moth, the imported cabbageworm, and the cabbage looper. 

Both foliar and root diseases can challenge cole crop production. Growers of leafy and heading brassicas have struggled with black rot and suspected downy mildew, and growers of root-crop brassicas are struggling with soilborne diseases.

Target pests and/or Beneficial Organisms

Swede midge, imported cabbage worm, cabbage looper, diamondback moth, flea beetles, cabbage maggots, black rot, downy mildew, lady beetles, parasitoids, spined soldier bugs.

Michigan State University