The Hunt to Learn How Much Herbicide is Intercepted by a Cover Crop

A thick stand of cover crops can help suppress weeds, but it can also intercept residual herbicides sprayed in the spring to control weed emergence. So how much herbicide is lost? And how much makes it through the thicket of residue to the ground? For many years, exact answers to those questions have remained elusive for farmers and researchers. 

But not for much longer! Led by Penn State University Extension Weed Scientist Dr. John Wallace, a multi-state team of researchers from the University of Delaware, Penn State and Virginia Tech are working to answer these very questions. 

Watch the video below to hear Penn State Master’s student Cody Smith explain the team’s goals and methods.

The research teams are hoping the petri dishes tucked into cover crop residue will unveil three big questions:

  • How much herbicide is initially intercepted by a cover crop?
  • How much herbicide is metabolized by the cover crop?
  • How much herbicide gets washed off the cover crop by incorporating rainfalls and makes it to the soil?
First, the researchers roller-crimp the cover crop mix (top left), place the petri dishes beneath the canopy (top right), spray the field with herbicides (bottom left), and finally, test the petri dishes for herbicide residues (bottom right). (Photo credits: Claudio Rubione, GROW.)

For more information on using cover crops for weed suppression, see this GROW webpage and these News Page stories

Video by Claudio Rubione, GROW; Text by Emily Unglesbee, GROW.