How to Save Glyphosate

Palmer amaranth

The question was directed to world-renowned weed-resistance expert Dr. Stephen Powles: “In the next 10 years, what will be the new Palmer amaranth in glyphosate-resistance management?”

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Powles’ answer was scary: “In the next 10 years, every weed we deal with in agriculture will be resistant to glyphosate unless we do something about it.”

Powles is Director of the Western Australian Herbicide Resistance Initiative at the University of Western Australia in Perth. Powles was dealing with glyphosate resistance in Australia well before it was even a gnat on an elephant’s back in the U.S. He was one of the featured speakers at the Bayer Respect The Rotation event in Memphis this summer.

“Roundup is the most revolutionary herbicide ever,” he said. “We may never see anything like it again. We have to do everything we can to protect it.”

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They say it’s always good to think out of the box, as long as you don’t think off the wall. They also say desperate times call for desperate measures, and these desperate times of resistance-management may require off-the-wall thinking.

“When you have a herbicide that is working, stop using it,” Powles said. “You think that’s crazy don’t you? Here’s why I say that: When you know you have something that you can rely on, stop using it and go to something else. You can always come back to the reliable product if the other product stops working. You’ve protected your reliable product.

“I’ll say it again so you can call me crazy again: When you find a product that is working, stop using it.”

Dr. Ford Baldwin of Practical Weed Consultants, LLC, in Austin, AR, shares Powles feelings for Roundup. “Roundup is one of my all-time favorite herbicides and I have a passion for saving it,” he said. “I’m a great fan of the Roundup Ready technology and it’s been a huge part of my career.

“It used to be when you looked in the back of a farmer’s pickup in Arkansas you typically saw beer coolers, hydraulic fluid, jumper cables, a big can of Freon and a few tools. But if you look in the back of a cotton farmer’s truck now, you see a bigger beer cooler and the rest of the bed of the truck is full of hoes.”

We just thought hand-chopping weeds had gone the way of the dodo bird.

Baldwin said that before resistant pigweed became a concern, we tended to think in terms of thresholds. “But that’s out the window. We need to think in terms of weed-seed populations,” he explained. “Population makes a tremendous difference in weed control, and that’s what you get with pigweed. They will just overpower you with numbers in a couple of years.”

Double Dip
Everyone understands the benefits of crop rotation and rotating insecticide modes of action. But have we thought much about rotating weed-tolerant systems? If not, then it’s time to, cotton grower Steve Stevens of Tillar, AR, believes.

“I joined the bandwagon like everybody else in the mid-90s with Roundup,” he said. “I bought into the deal that we weren’t going to have to use anything else. I figured out that wasn’t the case, but it took awhile.”

Now Stevens uses dual herbicide-technologies — Monsanto’s Roundup Ready Flex and Bayer CropScience’s LibertyLink, which is tolerant to the herbicide Ignite.

“Some of my neighbors tell me they can’t use a dual system — it has to be one or the other,” he said. “But this is the sixth year I’ve used Roundup Ready and LibertyLink, and I think we’ve proven you can.”

Dr. Ken Smith, University of Arkansan Extension weed scientist agrees that the Roundup Ready Flex system is not going away — “At least I hope it’s not,” he said — but it must be protected by whatever means possible.

“There are fields where you can’t use crop rotation,” he added. “So when you can rotate technologies, that’s wonderful. It just makes good resistance-management sense to flip-flop fields with Roundup Ready and LibertyLink.”

One of most important factors in a dual system is knowing exactly where you have Roundup Ready Flex varieties and LibertyLink varieties. Check and recheck before filling up the sprayer, Stevens advises.

“In my operation, I use Farmworks software as our mapping system,” said Stevens. “I send color-coded maps out with all of my planter drivers. One color will be for Deltapine, another for FiberMax and another for other varieties.

“Then we have color-coded herbicide maps, too. The driver is instructed to look at the map before he pulls into the field. We’ve only had one 10-acre error since we’ve been using a dual system, and none this year.”

Stevens said in 2011, Bayer will provide flags to place in fields at planting to mark where the LibertyLink system is used. Smith is working with the Arkansas State Plant Board on a standardized color-code system for each herbicide-tolerant trait.

Although there is some reluctance from Steven’s neighbors to go to a dual system, it’s a when not if situation. “We don’t have a choice,” he said. “I think the problems we have today are going to force us to use a two-system approach. With a little planning, you will have no problems.”

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