Ryegrass Stubborn No-Till Corn Problem

COLUMBIA - Mar 14/05 - SNS -- Ryegrass is an ongoing problem in no-till corn fields,, notes Andy Kendig, Extension weed specialist at Missouri University's Delta Research Center in Portageville, Mo.

"While glyphosate is usually an outstanding grass killer, ryegrass doesn't always burst into flames when treated. Often it just turns a funny color and sticks around."

Kendig said several management strategies can minimize the problem. "One trick for ryegrass control is to wait as late as you possibly can. We've almost always gotten excellent ryegrass control with late glyphosate applications; the March ones sometimes fail."

He advised farmers not to mix atrazine with glyphosate when spraying for ryegrass. Although that tank mix might work on other weeds, "we've seen significant ryegrass antagonism."

MU weed scientists have studied tank mixtures of ammonium sulfate and glyphosate on no-till weeds "and are hard-pressed to see an advantage," he said. "However, we have seen good boosts in ryegrass control when ammonium sulfate was added to glyphosate. I don't want to imply that it gives you a sure-fire cure, but it does help. Last year, we took a hard look at Select mixes. This did not seem to improve the ryegrass control from glyphosate."

He said "a relatively good treatment" is burning down fields with glyphosate, then "cleaning up" with an application of an herbicide that contains Accent, which "does a good job on ryegrass. Many growers are already making a Steadfast application for their overall corn weed control programs, and half of Steadfast is Accent."

Ryegrass is a problem in wheat as well as corn, Kendig noted. "We still talk to people who aren't aware that there are good herbicides which control ryegrass in wheat. The one key difference with these herbicides is that they should be used in the fall, shortly after wheat emergence." Despite the resistance of some ryegrass to common fall-applied herbicides, "you can grow wheat and still have good ryegrass control."