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New herbicide-resistance technologyNew herbicide-resistance technology

Paul L. Hollis

August 4, 2010

4 Min Read

New technology is on the way that will help growers with glyphosate-resistant Palmer amaranth pigweed. The big question is, will some growers survive until then?

“It depends on you,” said Stanley Culpepper, University of Georgia Extension weed scientist, speaking during the recent Sunbelt Ag Expo Field Day held in Moultrie, Ga.

Farmers from throughout the region braved temperatures topping 100 degrees for a preview of the latest in agricultural technology at this year’s field day.

Next year, says Culpepper, producers will be hearing more about Glytol Liberty Link technology from Bayer CropScience. “This will allow you to spray Roundup and/or Ignite over-the-top without injury,” says Culpepper. “We’re all familiar with the fact that with WildStrike cotton, we get injury when we spray Ignite. With Glytol Liberty Link, there will be no injury, and you have much more flexibility with the glyphosate or Ignite.”

Then, possibly in 2014/2015, there will be newer and more innovative technology, he says. “This will be cotton that is resistant to 2,4-D. You can spray 2,4-D right over-the-top of this cotton, and we hope to have some here next year for you to see. Or you can spray Banvel or Dicamba, as it was known back in the day. Both of these products can be used in a systems approach to control this weed pest very effectively and very economically.

“However, what you need to start thinking about is not the weed control system when you bring the 2,4-D technology or the Dicamba technology. It’s how can you manage Roundup Ready, Liberty Link, 2, 4-D or Dicamba. The technology is good, and the weed management systems will be good. But can you use the technology and protect yourself and not end up in court? That’s what we have to work on and figure out,” he says.

Glyphosate-resistant Palmer amaranth pigweed is devastating cotton production in Georgia, says Culpepper. “Across the state, we’ve confirmed it in 52 counties. If you’re not in an affected county, you probably will be this year. We all have resistance, and we will all see even more resistance as we move forward.

“The most important thing I can tell you is if you have resistance or you get resistance, and you keep doing the same things you’ve been doing, this pest will run you out of business. There’s no way you can survive,” he says.

Growers will need to become extremely integrated, says Culpepper. “That means you can continue to use herbicides, but you integrate those herbicides with other management practices. There are many potential ways of doing this, but I want to give you an example with some data we generated this year with some very large on-farm studies. If you are a typical grower strip-tilling into weeds, like 90 percent of our conservation-tillage guys do, and you go out with a very sound herbicide program at mid-season, you end up with 8,200 glyphosate-resistant Palmer amaranth per acre. In other words, you mow that crop down,” he says.

If a grower uses an extremely aggressive herbicide program, he only reduces the number down to about 7,600 plants per acre. Again, you mow your crop down if you’re going to rely exclusively on herbicides, says Culpepper.

An option, he says, is adding rye to the production system. “We plant rye in the fall, get it really big, roll the rye, and we use the exact same herbicide program as in the previous trials. We reduced the amount of Palmer amaranth that emerged by better than 50 percent simply by putting in rye. Think about all of this hand-weeding you’re doing. How much could you benefit just by growing rye in the fall?”

Conventional growers, says Culpepper, who deep-turn the land, would basically see the same response from rye, reducing the amount of emerged Palmer amaranth pigweed by 50 percent.

“For you to survive, you’ve got to figure out how to keep this Palmer amaranth from coming up. We have too many plants per given area for the herbicide to control them. We can deep-turn in the fall, and then use the rye — sort of a combination of the strip-tillage and conventional-tillage systems — and the soil isn’t sitting out there for the entire year to erode. If we integrate that into a herbicide program, we go from 640 emerged Palmer amaranth per acre down to 80 plants per acre. We just put in our layby, and I can tell you for sure right now that neither one of these systems will have a Palmer amaranth at harvest.”

Growers must become diversified, thinking about both tillage and cover crops, he says. “Growers need to think about changing what they’re doing if they want to survive.”

The Sunbelt Ag Expo Field Day gave farmers the opportunity to see more than 140 varieties of cotton, peanuts, corn, soybeans and grain sorghum from 25 companies. Also included was the latest pesticide and irrigation technology and the University of Georgia Cotton and Peanut Team’s applied research plots. Reinke Manufacturing Inc., a leading manufacturer of mechanized irrigation systems, demonstrated OnTrac, a comprehensive monitor and control system for irrigation systems.

e-mail: [email protected]

About the Author(s)

Paul L. Hollis

Auburn University College of Agriculture

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