Agricultural News
Herbicide-Resistant Weed Control. How Do We Go Forward?
Thu, 01 Mar 2012 16:59:01 CST
Herbicide resistant weeds are becoming a tremendous problem nationwide. And Andrew Wargo III sees the problem firsthand on a daily basis. Wargo is the business agent for Baxter Land Company out of Watson, Arkansas. It's an 18,000 acre operation growing cotton, rice, soybeans, corn, grain sorghum, wheat, and hybrid catfish.
Wargo spoke with Ron Hays at the Bayer Crop Science Ag Issues Forum in Nashville. He says weed resistance is a very serious issue and the days of easy farming are over.
While the problem may seem enormous, Wargo says it is manageable, but the solutions are far from easy. He says we first have to understand the problem. You have to understand the nature of the enemy and its strengths and weaknesses.
"You see them referred to as smart weeds or super weeds. Biologically, the weeds haven't changed. In any species in nature, there are a few items that don't follow the norm. We have selected for resistance by eliminating all those weeds that the chemical would control. The ones that are left thrive because they are very hardy and there's no competition."
Wargo says the problem of herbicide resistant weeds didn't just happen, it required a lot of help. He says the poster child of the "I told you so" crowd is the Round-Up-Ready crops, those that are tolerant of glyphosate. But the problem isn't necessarily the fault of the manufacturers, he says, but it is the power of glyphosate itself.
"We overused it," Wargo says. "I really don't fault Monsanto because the glyphosate actually kept American agriculture profitable during the 90s, but for a long time their solution to a failure to control was either to give us a better variety, a stronger variety, a super Round-Up if you will, or use it multiple times. So in about a 15-year period we did about 50 years worth of selection for resistance. And, due to market pressure, through the breeders, brought out crops-cotton, soybeans, and corn-that were round-up ready or tolerant."
In other words, farmers of all types developed a dependence on one herbicide. And even though producers "may have rotated crops, you didn't rotate your herbicide."
That over reliance simply allowed nature to take its course and allowed the most glyphosate-tolerant weeds proliferate.
It's taken about 30 years, but Wargo says there are those who have studied the problem and have developed solutions.
"The world's foremost authority on resistance is Dr. Stephen Powles of Australia and he says very simply, 'Whatever your weed control program is this year, if it's working, for God's sake, change it next year. Do not repeat. When you do, you're selecting for resistance. '"
While such an approach sounds simple-and is simple-on the surface, it is not easily implemented. The agricultural world has changed drastically in the last 30 years making implementing simple solutions very difficult.
"What is so maddening about the glyphosate resistance compared to others, always in the past we could go to another chemistry or a slightly different control. But we're not only dealing chemistry here, it was a crop production system. Cultivators were part, discs were part, most tillage implements were used maybe just once a year. And so farms greatly expanded, the labor force went down."
And so, Wargo said, returning to tillage and relying on it on a broad scale as a tool to combat herbicide-resistant weeds is not going to happen. The labor force is not there. The low-cost energy is not there.
"We can't go back."
The question then becomes, "If we can't go back, how do we go forward?"
The answer, he says, is to understand the weaknesses of the enemy and be prepared to exploit them. He says farmers must become pro-active in their approach to eradicating herbicide-resistant weeds.
A recent training program in Arkansas taught crop advisors and consultants not only how to identify insect problems, but also how to spot weed problems. Early detection of weed problems is crucial to being able to minimize and eradicate herbicide-resistant weeds.
"We've got to have early detection, we've got to use pre-plant or pre-emergence herbicides and not just figure on planting and then spraying. And if you have a failure, go ahead and bite the bullet and eradicate it with tillage, start over. Just don't produce seed," Wargo says.
"That's the one weak link in these resistant plants, particularly amaranths. After three years. 95 percent of the seeds are no good. So that, plus cover crop, it's going to be more work. The easy farming is over with."
Out of necessity, Wargo says, farmers will have to become more aggressive.
"We've got to rotate chemical modes of action, rotate crops. Be very judicious in our post-season management because corn, as an example, there's a lot of chemistry available in corn that will control the amaranth in corn. But you harvest the corn in August and its two months until frost time and you'll have a full production and you can't mow it. A bush hog just makes it grow horizontally instead of vertically. And it'll break seed on the ground. Plus some of these plants, amaranth in particular, both the male and the female produce viable seed. A big female with have ¾ of a million seed per plant, a big male about 300,000. Ninety-nine percent control of either one of those still doesn't get you anywhere because 10,000 seed on 43,000 square feet, that's one every four square feet. You still are not where you need to be."
Many of the major players are banding together to address this growing problem, Wargo says. Professionals from the government, to chemical companies, to county extension services are banding together to implement solutions. The largest part of the solution, he says is an ongoing effort to communicate, educate and adapt to rapidly changing conditions.
The herbicide-resistant weed problem is huge, Wargo says, but it is not insurmountable.
"We've got a massive effort ongoing to educate growers. Let them see what can happen in just one or two years. If they have a new species show up let them see how it's easier to be proactive and not permit seed reproduction on the front end rather than trying to clean up after. And communicate-growers, extension, chemical company reps. They can't afford to sell whatever pays the highest commission. They've got to sell what is effective. And we've all got to be good neighbors and good stewards."
You can hear Ron Hays' full interview with Andrew Wargo III by pressing the LISTEN BAR below.
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