Indiana: Purdue Offers Herbicide Resistant Weed Screening

    Waterhemp leaf extract prior to DNA extraction. Photo: University of Illinois Plant Clinic

    The Purdue Weed Science group is again offering herbicide resistance screening for Palmer amaranth, waterhemp, and giant ragweed for the 2018 growing season.  For Indiana residents, the resistance screens include ALS-inhibitor (group 2) assays for giant ragweed, as well as glyphosate (group 9) and PPO-inhibitor (group 14) resistance screening for waterhemp and Palmer amaranth.

    We test for the most common mechanism of PPO-inhibitor resistance in waterhemp and Palmer amaranth. We will not screen for glyphosate resistance for non-Indiana residents.

    PLEASE READ THE FINE PRINT: An important point to mention here is that researchers are discovering new mechanisms of resistance to these herbicides.  New mechanisms of resistance require us to develop new assays to test for these mechanisms.

    At the current time we do not have the capability to test for all of the known resistance mechanisms, but we can test for the mechanisms that are currently occurring most frequently in the field.  Please be sure to read the submission form and results form closely when you submit samples and receive results.

    Leaf tissue samples can be submitted for molecular DNA analysis that will allow results to be generated within a few weeks of submission.  It is important to follow the directions on the submission form for collecting, storing, and shipping leaf tissue samples as this can have a large impact on the accuracy of the results.

    A video demonstrating the proper sample collection and shipping process can be found here.

    Seed samples can also be submitted for analysis of herbicide resistance.  This allows us to also screen for glyphosate (group 9) resistance in giant ragweed.

    It is also important to follow the directions on the submission form for seed collection from the appropriate number of plants to assure quality results.  The seed samples will take several months to return results as plants will need to be grown from seed in the greenhouse.

    The submission form with instructions for collection, storage, and shipping can be found here.

    The submission form can also be found on the front page of the Purdue Weed science website.

    Please contact Julie Young (, 765-494-0891) or Todd Abrahamson (, 765-494-7071) with any questions or concerns you have when sampling or shipping a sample.

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