Loss of Control


By Cheryl Anderson
DTN Staff Reporter

OMAHA (DTN) -- Weeds left to have their way with corn and soybean crops can trim up to half of the yield potential. That's the assessment of a new report released by the Weed Science Society of America (WSSA).

The study assessed yield losses from 2007 to 2013, according to Anita Dille, professor of weed ecology in the Department of Agronomy at Kansas State University. Dille is the chair of the Weed Loss Committee of the WSSA, a professional organization of scientists from universities, industry and government agencies from both the U.S. and Canada.

Dille, who led the project, told DTN increasing issues with herbicide-resistant weeds was one incentive for the project. Recent reductions in research funding for weed management and a growing push for reduced herbicide application from the public were other motivating factors.

"We were curious as to what kind of impact weeds have now on our crops," she said. The project examined the economic losses annually if weeds were left uncontrolled. The WSSA team asked weed scientists to provide yield data from corn and soybean trials from plots left untreated for weeds and from plots using their best weed control methods. The difference between the yield from both plots was used to calculate the amount of weed loss.

The team also used statistics from the U.S. Department of Agriculture's National Agricultural Statistics Service and Statistics Canada for totals of corn and soybean acres harvested and the value of the two crops over the years. They found weeds left untreated can result in as much as $43 billion in crop losses annually in corn and soybean fields across North America.

The loss in corn yields without any weed management totaled 52%. The loss of untreated weeds to soybean crops resulted in a 49.5% total average yield loss.

"Dollars always give a really good picture of what kind of impact something can have."


Weeds remain a significant pest to manage despite advances in weed science, according to Dille. "They still figure out how to get past some of our best weed control practices," she said.

The study emphasizes the continued need for weed control research at a time when research dollars are declining. While there is industry support for evaluating weed control products, she emphasized the need for research outside of what the industry is doing.

"We scientists realize how important weeds are to manage. I think growers know that. But the research was an outreach to the public and regulatory agencies so they are aware of the impact weeds still have," she said.

Dille said that while the most recent report examined only the effects of weeds of corn and soybeans, future studies will study the toll of weeds in crops such as spring wheat, grain sorghum, vegetable crops, rice and cotton.

Details on the soybean study can be found here: http://bit.ly/…

Details about corn study can be found here: http://bit.ly/…

Cheryl Anderson can be reached at Cheryl.anderson@dtn.com