WASHINGTON, D.C. — As weeds become more resistant to herbicides, farmers, ranchers and scientists are looking for ways to combat the problem.

More than 250 people participated in a summit with the Weed Science Society of America on the problem of herbicide-resistant weeds. The goal of the Sept. 10 summit was to have these and other stakeholders discuss the issue. “If you continue to do the same thing on every field every year, things are going to get used to it,” said Harold Coble, retired agronomist, USDA Office of Pest Management Policy.

He learned to control weeds with a hoe but, for the past 15 years, herbicides have been a cost-effective method of controlling weeds. “We need to increase our understanding of resistance and what we can do to manage it,” he said.

“Modern weed management has allowed us to pay less attention than ever before, and we’re paying for that now. We can’t just spray our herbicide and go fishing and assume everything’s going to work well from now on.”

If a field has been sprayed with an herbicide, farmers need to check for weeds before they harvest the crops. If they harvest without checking for resistant weeds, then the seeds will scatter during the harvest, spreading and causing more problems.

Coble said farmers need non-chemical solutions for weed control. They need to have reliable resources to learn alternative methods, what will work and how long it will take to make money back.

He added farmers need to work together as communities to make changes and to report weeds that have shown a resistance to herbicides by growing in fields that have been sprayed. The plants need to be collected and sometimes burned to prevent the seeds from spreading.

He said he has heard of some new ideas that will help control weeds, but that is not enough. “It doesn’t matter how good technology is, we can’t do the same thing on every field,” Coble explained.

Jack Housenger, director of the U.S. EPA Office of Pesticide Programs, said the current goal is to extend the life of the herbicides and slow resistance by removing the resistant plants from the fields. Farmers also need to report any resistant plants, allowing early detection and containment.

Mandatory labels on how to use chemicals and best management practices need to be placed on all herbicides, allowing farmers to learn how to use the products, Housenger said. The labels would help provide education and training to extend the life of all pesticides.

“We don’t have a lot of answers yet. We have things we’re working on implementing,” he said. “We’re gaining an understanding of risk management of all pests, not just weeds.”

The current plan is to try to add mandatory labels, identify the problems early before they become a big issue and rely on scouting and reporting to find the resistant weeds, Housenger said.

“The tools we have now are still working, but we’re knocking those off,” said Michael Barrett, Iowa State University professor and extension weed scientist. “We need to do what we can to preserve them.”

He said recent research shows not tilling the ground is better for the soil, but tilling helps reduce weeds. Using cover crops, monitoring fields for resistant weeds before and after herbicides are applied, diversifying the herbicide used and weed management plans can help control weeds and reduce immunity to herbicides.

“Herbicides and pesticides have restrictions already on the label about how often you can use it for the environment. Too much regulation could remove an otherwise effective weed management tool,” Barrett said.

Any required labeling and regulatory action would need to be carefully considered. “The threat of credible regulatory action will very often encourage people to do what they don’t want to do,” he added.

Jill Schroeder, weed scientist and agronomist with the USDA Office of Pest Management Policy, said the current approach is not effective.

“Something is not working right in terms of how we are delivering our messages and how they are being received,” she said. “Our message must be consistent and science-based.”

Catherine Woteki, undersecretary and chief scientist for USDA’s Research, Education and Economics Mission, said the summit was a call for action based on a candid discussion. She explained some herbicides worked so well that farmers stopped scouting fields for weeds. In 2000, more than 70 percent of them still scouted fields; in 2010, only about 40 percent still scouted for weeds. The remaining farmers relied on the herbicides.

“The hope is that everyone is committed to doing our part to develop workable decisions ... The task is challenging because it varies based on the region of the country and the crop,” Woteki said.

More meetings are being planned about this issue.