Regulators Eye New Restrictions To Address Herbicide-Resistant Weeds


   From Montana to Maryland, to Brazil and as far away as Turkey, new “super weeds” that are resistance to certain herbicides are threatening to rob profits from farmers and could force dramatic changes in production and harvesting systems – challenging hard-fought gains in conservation practices that protect soil and water. New regulatory actions are already being discussed to address the issue.
   “Cold, hard steel may have to become part of my system again,” noted Montana farmer Gordon Stoner, in reference to tillage tools that can bury weed seeds deep enough to prevent emergence. Stoner joined other growers from around the globe to share their experiences with weed resistance at a global symposium sponsored recently by Bayer.
   The global crop protection company, based in Monheim, Germany, says the number of herbicide resistant weeds is growing fast and the economic threats are very real. Weeds are the single most important reason for crop losses globally, causing high management costs and threatening food security, the company notes in a fact sheet about its own integrated weed management program.
   To date, 247 different species have developed herbicide resistance in 86 crops and 66 countries, according to the International Survey of Herbicide-Resistant Weeds, posted on
   The organization also posts an interactive map, showing resistant weeds by state in the U.S.  
   “It’s not a question of if (weed resistance becomes a problem), it’s when,” says Stoner, who has not officially documented weed resistance on his own farm, but sees the problem emerging in nearby fields. For now, he’s been fighting off weed pressures by using crop rotations and multiple tank mixes of herbicides at the maximum recommended rates. 
   And he’s thinking about plowing, even though Stoner long ago parked his tillage tools and has been using 100 percent no-till practices on his 12,000 acre farm, situated in the northeast part of Montana near the Canadian border. 
   In fact, weed resistance could become so bad that, Stoner, who serves as vice president of the National Association of Wheat Growers, joked that the next national commodity organization may be the “National Weed Growers Association.” 
   It’s a threat that organizations representing corn, cotton, soybeans and wheat are taking seriously, according to staff and elected officials attending the meeting. They know there is not any one “silver bullet” coming down the pesticide pipeline as a solution. Yet, many of them acknowledge that, given low commodity prices - many growers would like to “keep on keeping on” with easier and cost-effective current practices, which often involve spraying glyphosate (Roundup) to kill weeds over their Roundup-ready crops. That is, until the issue hits them head on. 
   For Chip Bowling, president of the National Corn Growers Association, weed resistance challenges hit home about 4 years ago on his farm, located about an hour south of the District of Columbia. Palmer Amaranth, a species of pigweed, arrived “fast and furious” in his fields and was resistant to glyphosate.  
   He immediately worked to contain the problem, which emerged on 3 of the 27 different units he farms, employing tactics like spraying costly new herbicides, planting cover crops and washing his combine after harvesting each field. For Bowling, who is careful to protect any herbicide or nutrient that might run into the nearby Chesapeake Bay, weed resistance presents multiple challenges. 
   “My non-farm friends don’t like to see me running the sprayer, but they also don’t want to see big patches of weeds. From an economic standpoint, I need to spray and keep weed pressures down and yields up or I won’t be able to make a profit.”  
   In order to help growers better understand and address weed resistance, the United Soybean Board, a handful of commodity organizations, crop chemical companies and land-grant universities launched an educational web site last year called “Take Action on Weeds.” ( ) It’s a start, but farmer leaders say more work is needed.
   Many growers know product brand names, but don’t understand the different modes that products kill weeds – a crucial piece of knowledge for fighting weed resistance, observers say. In addition, they need to be able to access the right pesticides at the right times from local retailers.
   “We’ve made a lot a progress but we are still very reactive in our approach,” noted Arlene Cotie, Product Development Manager for Bayer. “We need to have one voice in the U.S. on the sense of urgency to do everything we can to be cost-effective and competitive in the global market by managing resistant weeds,” she emphasized. 
   EPA officials have already been keeping a close eye on the situation and the scrutiny is expected to be more intense in the future, according to Yu Ting Guilaran, Director of the Office of Pesticide Programs, who also spoke at the symposium. 
   The agency already signaled a renewed emphasis on weed resistance management with the 2014 approval of Dow’s Enlist Duo, a combination of 2,4-D and glyphosate, she noted. The terms of the registration impose requirements on the manufacturer including: robust surveying and reporting to EPA; grower education; and remediation programs. Going forward, she said weed resistance management will be a focus for all pesticides coming in for EPA reregistration and suggested the need to develop a risk-based framework that includes training, education, early detection, mitigation, and clearer product labels. ∆
   SARA WYANT: Editor of Agri-Pulse, a weekly e-newsletter covering farm and rural policy. To contact her, go to:
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