WASHINGTON, Oct. 7, 2015 - From Montana to Maryland, to Brazil, Bavaria and as far away as Turkey, new “super weeds” 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. Will new regulatory actions come next?

“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 some emergence. Stoner joined growers from around the world to share their weed resistance experiences at a global symposium sponsored by Bayer in Paris last week.

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, Bayer says in a fact sheet promoting its own integrated weed management program.

To date, 247 different species have developed resistance in 86 crops and 66 countries, according to the International Survey of Herbicide Resistant Weeds, posted on www.weedscience.org.

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 various 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 weed resistance issue hits them head on.

For Chip Bowling, president of the National Corn Growers Association, weed resistance challenges hit home about four years ago on his farm, in Maryland, 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 three 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 website 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 of action that 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 EPA’s 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 said. 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 she suggested the need to develop a risk-based framework that includes training, education, early detection, mitigation, and clearer product labels - among other things.


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