Giant ragweed in Wisconsin: Management and herbicide resistance status
2021
- Department of Agronomy, UW Madison
Project Media
Giant ragweed (Ambrosia trifida) has become one the most difficult weeds to manage in row crops
in the U.S. Corn Belt. Due to giant ragweed’s early emergence, rapid growth and biomass accumulation,
high photosynthetic rate, and ability to adapt to diverse environments, when no properly managed it can
quickly outgrow and outcompete the crop and other weeds for resources such as water, nutrients and light.
The extended emergence window of some giant ragweed biotypes makes it difficult to control this weed
with POST-emergence herbicides alone. Moreover, ALS- and EPSPS-inhibitor resistant giant ragweed
have been confirmed in 7 and 12 U.S. states, respectively, including Wisconsin. These characteristics and
current state of herbicide resistance indicates a need for effective integrated management strategies to
control giant ragweed season long.