Rotating herbicide chemistry, including switching mode of action not just products, will reduce potential for resistant weeds to take over. “Also limit the number of applications for any mode of action in any one year.

“Using more than one herbicide chemistry in a given year is an extremely important practice in managing weed resistance,” Shaw said. “That may cost a little more than relying on only one product, but you get enough of a yield bump to get to break even. From a net return standpoint, a pro-active approach is better. Reactive tactics will be more costly.”

Shaw said herbicide mixtures help with resistance management. “Both chemistries must have a high level of activity on target weeds and they must have different modes of action,” he said. “Also, monitor fields within, and across years carefully.”

He said farmers should watch for weeds that are more difficult to control than usual or are of a species known to be resistant in other locations, even in other states.

Farmers are getting help. “Most Extension specialists have statewide efforts in place to educate growers, dealers, distributors, consultants, state agricultural agencies and the public.

“Extensive research efforts have been developed in states where resistance is occurring. Monitoring efforts are widespread and industry and universities are working to eradicate new outbreaks as much as possible.”

Shaw said efforts should be focused, targeting appropriate groups, including media, growers, dealers and distributors, and consultants. “Information must be accurate,” he said. “And the message must be consistent and urgent.”

He recommends mode of action labeling on herbicide containers to make producers aware of what they apply.

He said a double-handful of organizations is involved in developing educational materials including: the National Research Council, the National Cotton Council, the National Corn Growers Association, the American Soybean Association, National Association of Conservation Districts, Herbicide Resistance Action Committee, CropLife America, USDA-APHIS, USDA-NRCS, USDA-NIFA, and EPA.

“Glyphosate resistance is here to stay,” Shaw said. But he also acknowledged that the industry needs more science to understand the effectiveness of resistance management practices. “We also need to learn how to keep it from happening again.

‘We have enough tools and knowledge to do what needs to be done.”

rsmith@farmpress.com