Resistance Management School: How to test for herbicide resistance

There are a number of reasons why herbicides sometimes fail to control weeds.

Perhaps surprisingly, one of the easier things to rule out is whether the weed is herbicide resistant. Ontario Ministry of Agriculture, Food and Rural Affairs weed specialist Mike Cowbrough says many universities across Canada conduct testing for herbicide resistance, but growers have to ensure they collect a proper sample.

Over the past 20 years, Cowbrough notes that about 20 percent of the weed seed samples submitted to the University of Guelph could not be processed for testing. That’s mainly because the sample contained immature seed, there was no seed in the sample, or there were too few plants.

In this episode of RealAgriculture’s Resistance Management School, Cowbrough provides tips on how to best collect samples of common weeds and grasses found in Ontario, including common ragweed, common lamb’s-quarters, pigweed, and foxtail. He notes that the best time to sample these species for testing is mid to late September

When gathering weed samples, he advises growers to get as much seed as possible of the suspected resistant weed and be sure to grab a representative sample from across the field.

Click here for more Resistance Management School episodes.


Bernard Tobin

Bernard Tobin is Real Agriculture's Ontario Field Editor. AgBern was raised on a dairy farm near St. John's, Newfoundland. For the past two decades, he has specialized in agricultural communications. A Ryerson University journalism grad, he kicked off his career with a seven-year stint as Managing Editor and Field Editor for Farm and Country magazine. He has received six Canadian Farm Writers' Federation awards for journalism excellence. He's also worked for two of Canada's leading agricultural communications firms, providing public relations, branding and strategic marketing. Bern also works for Guelph-based Synthesis Agri-Food Network and talks the Real Dirt on Farming.


Wheat Pete’s Word, Dec 5: Corn wintering strategy, wet wheat, potato shortages, and the theatre

This week's edition of Wheat Pete's Word tackles tough questions and comments from the Maritimes, the United States, and across Ontario. In case you missed it, the east has called time-of-death on the potato harvest with a full 10% of the crop abandoned. There's no shortage of concern for next year's wheat crop, too, and…Read more »


Leave a Reply


This site uses Akismet to reduce spam. Learn how your comment data is processed.