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Rotation Study

Crop Rotation and Its Effects on Corn Rootworm Populations

Situation: Farmers are changing crop rotations as they address shifts in corn demands and relative crop prices. The market penetration of transgenic corn with Bt-RW traits has been rapid and extensive. These traits have the potential to affect corn rootworm populations more intensely than soil insecticides. What do these changes mean for corn rootworm populations and the risk of injury and loss?

Project Description: The study is designed to explore effects of crop rotation on corn rootworm populations and subsequent damage. This study conducted at UMORE Park (Rosemount) and the Southwest Research and Outreach Center (Lamberton) relies on large plots (ca. 90 ft X 90 ft) to minimize any edge effects on corn rootworm activity. The rotation study design features six treatments (continuous isoline corn protected by Force, continuous Bt-RW corn, corn/soybean rotation with odd-year isoline corn protected by Force, corn/soybean rotation with odd-year Bt-RW corn, corn/soybean rotation with even-year isoline corn protected by Force, corn/soybean rotation with even year Bt-RW corn). Data will be gathered on effects on root injury, adult emergence, activity, egg laying and yield. Analyses will address whether or not egg-laying is occurring in soybean alone, the extent of egg laying associated with the volunteer corn, and the effects of crop rotation and volunteer corn on root injury and yield. A complementary study this year will determine how presence or absence of the Bt-RW trait affects corn rootworm population dynamics.

Expected Outcomes:

  • Improve understanding of how risk changes as farmers switch from rotated to continuous corn.
  • Document on how continued use of Bt-RW corn affects corn rootworm populations
  • Compare relative performance of Bt-RW corn, soil insecticides, and crop rotation in their effects on corn rootworm populations
  • Determine whether or not CRW, especially NCR, lay eggs in soybean.
  • Provide data for modeling of resistance management strategies.

Funding and Logistical Support: This research is funded by the Minnesota Corn Research and Promotion Council and the MN Legislative Agricultural Response Fund. Seed was provided by Pioneer Hi-Breds.

Kenneth Ostlie
Professor and Extension Entomologist
University of Minnesota
Department of Entomology
1980 Folwell Ave., Rm. 219
St. Paul, MN 55108-6125
Cell: (612) 750-0993
Office: (612) 624-7436
Fax: (612) 625-5299
Email questions on corn rootworm