Calculating the cost of uncontrollable weeds

If farmers lost their weed-management toolbox, what economic impact would that have? Experts at the Weed Science Society of America (WSSA) punched the numbers, and the price tag is costly, indeed.

WSSA researchers determined that without herbicides and other control techniques, about half of U.S. corn and soybean yields would get swallowed up. The cost to farmers - $43 billion annually.

"It's an astonishing number and indicates the significant threat weeds present to crop production," says Anita Dille, Kansas State University researcher and chair of the WSSA Weed Loss Committee.

"It also drives home the importance of taking steps to mitigate the development of herbicide resistance.

When a single herbicide is used repeatedly to the exclusion of other controls, weeds can become resistant and can grow unchecked."

Dille and fellow researchers developed crop loss estimates by looking at data from seven years' worth of weed control studies. The average yield reductions reported from these studies was 52.0% in corn and 49.5% in soybean.

The committee focused on corn and soybean production due to their importance to North American agriculture - between the U.S. and Canada, farmers grow corn and soybeans on approximately 170 million acres.

Additional analysis from WSSA is available at

Worried about a particular weed in your fields? Use the AgWeb weed field guide, which has photos and notes on 74 different economically significant weed species. Visit to get started.