January 2014, Wheatlife
By Drew Lyon and Ian Burke
Glyphosate-resistant weeds are making headlines in the Midsouth and Midwest where the use of Roundup Ready® corn, soybean and cotton have created the perfect conditions for selecting weeds resistant to this “once in a century” herbicide.
On a global basis, weeds such as rigid ryegrass (a close cousin of our local Italian ryegrass), goosegrass and johnsongrass have also evolved glyphosate resistance. Do wheat growers in the PNW need to be concerned? The short answer is yes. Globally, weeds have evolved resistance to 21 of the known 25 herbicide sites of action and to 148 different herbicides.
There are currently 13 different species with “known” herbicide-resistant biotypes in the PNW. Combined, these biotypes are resistant to a dozen different mechanisms of action. As opposed to “mode of action” which refers to all the plant’s processes affected by a herbicide, the “mechanism of action” refers to the biochemical site within a plant that a herbicide directly interacts with. It is highly likely resistance biotypes exist that we know nothing about. Read more