Fighting back against giant ragweed
If you grow corn or soybeans in the Upper Midwest, you've probably battled giant ragweed. Now, a new survey published in the journal Weed Science offers insights into the distribution and management of giant ragweed, which can cause big losses in...
If you grow corn or soybeans in the Upper Midwest, you’ve probably battled giant ragweed.
Now, a new survey published in the journal Weed Science offers insights into the distribution and management of giant ragweed, which can cause big losses in corn, soybeans and cotton. The weed is a growing concern, especially as more giant ragweed plants become herbicide-resistant.
Weed Science is a journal of the Weed Science Society of America, a nonprofit scientific society focused on weeds and their impact on the environment.
According to the Weed Science Society, a team of researchers from six universities and the U.S. Department of Agriculture’s Agricultural Research Service surveyed certified crop advisors working in the Corn Belt regions of the United States and Canada. The survey explored the prevalence of giant ragweed and gathered information on crop production practices. The
responses led to several key findings:
Distribution and spread. Results suggest that giant ragweed is spreading outward from crop fields in the east-central U.S. Corn Belt. The weed currently is most prolific near the upper Mississippi River and its major tributaries, as well as north of the Ohio River in Indiana and western Ohio.
Herbicide resistance. Nearly 60 percent of counties represented in the survey have giant ragweed populations that are resistant to ALS-inhibiting herbicides, to glyphosate or to both.
Impact of crop production practices. Giant ragweed populations are highest in fields that are managed with minimum tillage, planted continuously with soybean crops and treated with multiple applications of a single type of herbicide.
Impact of ecological factors. The abundance of giant ragweed in crop fields was highly correlated with its abundance in nearby noncrop environments. Populations of giant ragweed were highest in counties that offered early and prolonged periods of emergence and in crop fields with large populations of seed-burying earthworms.