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With its deep root system that breaks up compacted soils, annual ryegrass is an attractive cover. But those deep roots can also make it a challenge for no-tillers to burn down.
Barry Fisher, Indiana state agronomist with the Natural Resources Conservation Service, and Dan Towery, president of Ag Conservation Solutions, say it’s critical to know the growth pattern of annual ryegrass.
Roots can grow up to 51 inches deep, which means basic burndown management used in a traditional corn-soybean rotation won’t work if the weather is cold, they told attendees at the 16th annual National No-Tillage Conference.
Optimizing your burndown is critical, since misapplication can simply knock down ryegrass and allow it to come back.
“A few years ago, we had several farmer demonstration plots for the Indiana Conservation Tillage Initiative. In a few fields, we used a tankmix of glyphosate and atrazine, which is typical for the area,” Fisher says. “A lot of commercial dealers use this mixture on no-till fields since they’re trying to take out winter annuals.”
That didn’t work on the annual ryegrass as the atrazine caused antagonism with the glyphosate by inhibiting translocation.
“We came back about a week later, sprayed it again with Roundup before the crop was up, and it kept coming back,” Fisher says. “The initial spray weakened the annual ryegrass, which made it more difficult to completely kill as it wasn’t actively growing.
“I covered the field with an ATV sprayer using a post grass herbicide. That still wasn’t enough and…