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When a no-tiller decides to add a cover crop to his farm system, there may be a number of results he’s hoping to achieve, and weed control is likely one of them.
A 2012 survey by Sustainable Agriculture Research and Education (SARE) found that weed control was the fourth highest among 15 desired benefits farmers were seeking from covers.
At the 22nd National No-Tillage Conference held earlier this year, University of Missouri weed scientist Kevin Bradley shared three things growers must keep in mind if they plan to use cover crops to suppress weeds.
“This is going to differ based on your geography and maybe even in some of the varieties you use,” Bradley says.
Bradley tested the effectiveness of different herbicide treatments on a number of cover-crop species at its Columbia, Mo., research site. Wheat, cereal rye, annual or Italian ryegrass, crimson clover, hairy vetch, radish, Austrian winter peas and a cereal rye-vetch mix were either sprayed on either April 5 or May 1.
Since the radishes winterkilled, the study from 2013 found cereal rye was the easiest cover to kill, using treatments that included 28 ounces of Roundup that were effective for both application dates. Treatments with 4 pints of Gramoxone applied on May 1 also terminated cereal rye.
The study also had good success in terminating hairy vetch and Austrian winter peas. Bradley thinks using a growth regulator on legumes is what really increases their termination rate.
Cover crops more difficult to terminate included…