Herbicide Resistant Weeds in Michigan

Glyphosate resistant common waterhemp in Michigan

Submitting your weed seed sample for testing

  • FORM– Screening for herbicide resistance at MSU Diagnostic Services
  • Testing includes multiple sites of action, based on seed quantity and quality – $90.00
  • MI Soybean growers qualify for free testing of the following species courtesy of the
    Michigan Soybean Promotion Committee:

    • Palmer amaranth
    • Waterhemp
    • Horseweed/marestail
    • Common lambsquarters
    • Common ragweed
    • Giant ragweed
  • Testing of other species may be possible in consultation with the Weed Diagnostician, Erin Hill (hiller12@msu.edu)

Weed seed is required to conduct a whole plant bioassay in the greenhouse to screen for herbicide resistance. Mature, high quality seed or seedheads should be collected from suspicious plants in the late summer or fall; ideally pooled samples with seed/seedheads from 5 or more plants will ensure adequate seed quantity. For species specific seed collection and submittal information please refer to the top link above. Screens will be designed by herbicide site of action (e.g. EPSP synthase inhibitor, ALS inhibitors, Photosynthesis inhibitors, etc.) and are generally available 2-3 months after submission to allow for seed cleaning, dormancy breaking measures, greenhouse growth, herbicide application, and evaluation.

Cumulative map of herbicide resistant weed species in MI (updated April 2018)Herbicide resistance map showing species distribution in Michigan, read listing by county for details

Weed Management Resources for Michigan

MSU Field Crops Weed Science Group– Department of Plant, Soil and Microbial Sciences

MSU Vegetable and Fruit Weed Science Group– Department of Horticulture