What losses would corn and soybean growers experience if they were forced to eliminate herbicides and other control techniques from their weed management toolbox?  A team of experts with the Weed Science Society of America (WSSA) found that in the U.S. and Canada, about half of both crops would be lost to uncontrolled weeds, costing growers about $43 billion annually.

“It's an astonishing number and indicates the significant threat weeds present to crop production,” says Anita Dille, Ph.D., of Kansas State University 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.”  

To develop their crop loss estimates, Dille and her team gathered data from weed control studies conducted over a seven-year period.  They found an average yield loss of 52 percent in corn and 49.5 percent in soybean crops when all weed control practices were eliminated. To determine the financial value of the crop-loss estimates, the committee used average commodity prices published by Statistics Canada and by the USDA's National Agricultural Statistics Service.

The committee focused its work on corn and soybean production due to the prominence of both crops in North America. According to the United Nations Food and Agriculture Organization, the United States ranks 1st in the world for both soybean and corn production, while Canada ranks 7th and 11th, respectively. Together the two crops are grown on approximately 170 million acres across those two countries. 

Further data from the WSSA crop-loss study is available at http://wssa.net/wssa/weed/croploss. Details also will be published in an upcoming edition of the WSSA journal Weed Technology.  Further information on herbicide resistance is available at http://wssa.net/wssa/weed/resistance.