The spread of herbicide resistant weeds is a growing problem in many parts of the United States. Although herbicide resistance has existed for decades, the number of weed species with resistance to glyphosate and other herbicides has risen dramatically in recent years.
As a result, more time and money are being spent on weed control. In addition to lower yields and profits for farmers, some conservation gains that have been accomplished with reduced or no tillage systems may also be reversed unless changes in weed management are implemented.
An interdisciplinary team of weed scientists, economists and sociologists led by Mike Owen, Iowa State University agronomy professor and extension weed specialist, are working to develop effective approaches to address this growing problem of herbicide resistant weeds.
“As the people on the front lines of herbicide resistance, farmers have a unique experience and understanding of the problem and the opportunities for cost-effective approaches, which makes the information they can provide so critical for effectively responding to the herbicide resistant weed problem,” said Owen.
The survey will help the team better understand the human dimensions of herbicide resistance and how herbicide resistant weeds are spreading. It will determine how farmers manage weeds, including the use of herbicides, tillage systems, crop rotation, and other practices that have significant impacts on herbicide resistance.
Owen notes that the many weed issues from the past continue to plague Iowa’s farmers, particularly the weed, and water hemp, in soybean fields.
“There has not been a notable increase across the state in major weed management failures,” according to the weed specialists. “However, random surveys suggest that a high percentage of fields with weeds visible above the soybean canopy have evolved resistance to one or more herbicides.” They conclude that herbicide-resistant weed populations are slowly increasing.
The two experts advise farmers that now is the time to make adjustments to their weed management programs before weed densities become worse. Their suggestions include diversifying types of herbicides as well as paying attention to how and when they are used.
A guide was written by the professor and weed specialist Bob Hartzler and is now available online at Iowa State University Extension Store and provides industry updates and gives instructions on how to design resilient herbicide programs to manage herbicide resistance. The resilient herbicide programs rely on multiple herbicide groups to manage weeds, and the new publication details successful approaches. Non-herbicidal strategies also are included.