By Tim Kowols
Farmers are being asked to double check their fields after an herbicide-resistant weed was found in southern Door County. A waterhemp plant was discovered to be glyphosate-resistant, which is the active ingredient found in common herbicides used to protect fields from weeds and pests. Extensive crop rotation in Wisconsin had warded off the resistant weed in the past compared to other parts of the country but is now found currently in 17 counties. Door County UW-Extension agriculture agent Annie Deutsch says this case provides a good example why farmers and gardeners should periodically reexamine their weed management strategies.
While resistance over time is natural, Deutsch recommends avoiding factors that can cause poor herbicide performance including poor mixing, unfavorable environmental conditions, and using the herbicide rate at below the recommended level. So far there have been no confirmed cases of the glyphosate-resistant waterhemp in Kewaunee County. You can learn more about pesticide-resistance management and what to do if you find it on your property online with this story.