While choosing the right cover crop, or mix of covers, for a farm can be a challenge, there’s also an art to terminating covers that don’t winterkill with the right products at the right time.

Taught to stay out of fields when they’re too wet, no-tillers can face a real dilemma during heavy spring rains. Last May, much of the southern Midwest had 20 or more inches of rain, with parts of Illinois seeing 12-13 inches alone last April.

Letting cover crops grow too much and reach maturity can cause issues, even if a no-tiller’s stated goal is building biomass, says retired University of Illinois Extension agronomist Mike Plumer.

“You need to be able to terminate when you want to terminate,” Plumer said during the 25th annual National No-Tillage Conference in St. Louis earlier this year. “But rather than having a hard core plan on how you’re going to manage your cover crops, try to be a little bit flexible.”

Target Vegetative Stage

One key to improving termination results is to understand how cover crops grow and uptake the herbicide.

Ideally, no-tillers should target termination for when cover crops are in the vegetative stage and actively growing, so the systemic herbicides are taken up efficiently. For example, this means killing grasses before…