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• With well over 100,000 acres of cotton and about a half million acres of soybeans planted this year in Virginia, concern is growing among producers as to the best tools available to manage Palmer amaranth and other herbicide tolerant weeds.
A good option
One of the options for growers to use, if they have glyphosate resistant weeds or want to reduce chances of having the problem is planting a LibertyLink cotton or soybean variety and using Ignite herbicide.
The system is similar to a Roundup Ready program in terms of being easy to use and for that reason alone Holshouser contends it will be a logical choice for growers who have depended on glyphosate for many years.
“LibertyLink will force growers to be better weed managers. It won’t kill weeds nearly as large as will glyphosate. Unlike glyphosate, LibertyLink and Ignite will not allow growers to do a salvage spray, like many growers did with glyphosate, he explains.
“I really think we need to focus on using LibertyLink soybeans, especially, in fields that have been in total, or near total, glyphosate weed management systems for three years or more. There are plenty of fields in the state in that category, Holshouser says.
Many growers have been reluctant to use genetically altered varieties in soybeans and cotton because of well documented yield drag on some varieties.
Now, Holshouser contends, LibertyLink-containing varieties are among the top yielding varieties in statewide variety testing, producing 3-5 bushels per acre more than average in state-wide testing.
Unfortunately for Virginia growers, glyphosate resistance isn’t the only problem they will face in the future.
In Southeast Virginia, veteran Crop Consultant Wendell Cooper says he checks some fields with pigweed, marestail and ragweed — all with varying degrees of resistance to glyphosate.
This year marestail came in much later than usual. In fields with glyphosate resistance, the combination of resistant pigweed and ragweed, plus marestail late was a tough one for growers to handle, he says.
One combination that Cooper says has looked good so far this year is LibertyLink, both in Widestrike cotton and in FiberMax and Stoneville varieties. “There isn’t a lot LibertyLink cotton in the area that I work, but what I’ve seen looks really promising,” Cooper says.
Glyphosate resistant ragweed isn’t widespread across Virginia, but in fields where it is resistant it can be a major problem. Ignite, the herbicide used on LibertyLink crops, is very good on ragweed, according to Cooper.
“It also works real well on marestail and will do a good job on pigweed, if the grower can spray these weeds before they get taller than 4-5 inches,” he adds.