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Across the Midwest, weeds have become resistant to glyphosate and other heavily used herbicides as growers use the same herbicides over and over.
With today’s newer herbicide-resistant technologies, it’s tempting to take the easy way out and overuse the technology. Rotating herbicides and selecting different modes of herbicide action will help to reduce the potential of weed resistance on your farm and improve weed control.
During the past 13 years, many Midwestern states have reported one or more glyphosate-resistant weeds, such as giant ragweed, common ragweed, waterhemp or horseweed.
Dr. Chris Boerboom, Extension weed scientist at the University of Wisconsin, points out that an important practice to slow or avoid the development of resistance altogether is to reduce glyphosate usage by rotating herbicide modes of action.
Two ways to help reduce the chances of resistance is to use conventional herbicides in corn and then use glyphosate in soybeans; and/or apply a pre-emergence herbicide followed by glyphosate in the same season. No-tillers should really consider adding 2,4-D to their glyphosate burndown treatments.
The best management decision may be to plant herbicide-resistant crops, but use conventional herbicides on one of the crops in the rotation to reduce the potential of weeds developing resistance to glyphosate.
This still allows you to use glyphosate if a situation develops where you couldn’t get the crop sprayed on time with the conventional herbicides and/or if your weed control fails and you need a rescue treatment.
Saving the technology for situations where you really need…