What is in this article?:
With the proliferation of herbicide-resistant weeds in crop fields, Larry Steckel has some not-so-good news for Mid-South farmers: “Nothing about weed control is going to be as easy as it once was. Even with the new technologies in the pipeline, weed control is going to be much more complex. The good old days of weed control with two or three shots of Roundup over the top are gone and are never coming back,” he said at the annual conference of the Mississippi Agricultural Consultants Association at Mississippi State University. “We’re just running herbicides into the ground one after another.”
A longer window of vulnerability
With Palmer pigweed, Steckel says, “We’ve got to start thinking about weed control as 30 days before we plant the crop to 30 days after we cut the crop — there’s a much longer window of vulnerability now. From the time you cut your corn until the first frost, your fields can build up a heavy load of pigweed seeds.
“One thing I tell growers who have a pigweed problem in soybeans is to rotate to corn; there are a lot of herbicides that will do a good job of controlling pigweeds in that crop.”
Clarity herbicide has done a good job of controlling marestail, he says, “but from walking fields in west Tennessee, I’m wondering if we aren’t beginning to see some tolerance for this product. The 8-ounce rate isn’t as consistent as it was a few years ago. A lot of farmers in west Tennessee are no longer using the 8-ounce rate; 10 or 12 ounces is fairly common now.
“We’ve looked at Sharpen for five or six years, and in research work it has been outstanding on marestail in some years, not so much so in others. Integrity, which was a premix of Sharpen and Outlook, was more consistent. It has been renamed Verdict and will be labeled at a 5 ounce rate on soybeans preplant and preemergence. If you’re going to look at a Sharpen product, this would be the one to go with.”
The LibertyLink technology is being readily adopted by farmers, Steckel says, “but I have concerns about its stewardship and management. The way we’re going, I’m afraid we could see resistance in three to five years.” Down the road, he says, the Dow Herbicide Trait (DHT) can be used with 2,4-D in cotton, and with Fusilade, Assure, and 2,4-D in corn. “The ETA for approval in corn is 2013 and cotton/soybeans 2015. In our research, the crop tolerance is outstanding.
“Glytol LibertyLink is also going to be a useful tool in cotton. Looking at new technologies, I think the dicamba trait and the 2,4-D trait will be useful tools to help bail us out of this glyphosate-resistance quandary.
“But,” Steckel emphasizes, “my take home point about herbicides is this: We must — we must — keep Ignite and Flexstar and the PPOs in play for Palmer pigweed for the next three to five years until we can get to these new technologies.
“If we can manage these two herbicides so pigweed doesn’t develop resistance to them, we may be able to ride herd on this weed long term. If we use rotation, different modes of action, and don’t rely on just one herbicide, I think we have a chance.”