Can Cover Crops Slow Herbicide Resistance?
Herbicide resistance is a costly and growing problem. In fact, many weed populations now exhibit resistance to multiple herbicide mechanisms of action.
Researchers recently conducted field experiments to explore how cover crops influenced the management of horseweed in no-till grain crops. They found that winter hardy cover crops reduced horseweed density by 52% in year one and 86% in year two. With fewer horseweed plants to treat before crops were planted, there was a reduced herbicide workload and a lower selection pressure for resistant weeds.
Cover crops also reduced the size inequality among horseweed plants, meaning fewer large plants were found at the time of pre-plant herbicide application. Researchers say size uniformity reduces any size-dependent fitness advantage for biotypes that develop resistance.
What do we do with this information? Scientists say that understanding the complementary relationship between cover crops and herbicides can lead to new weed control strategies designed to slow the development of herbicide resistance.
Want to know more? You can read the full text of the article “Cover crop effects on horseweed (Erigeron canadensis) density and size inequality at the time of herbicide exposure” in Weed Science Volume 67, Issue 3.
Photo credit: Above: Horseweed (Erigeron canadensis) courtesy of Shutterstock. Below: Horseweed in the field, courtesy of WSSA