The early spring warmth that gave Michigan alfalfa a jump on the growing season may have led to problems with winter-annual weeds such as common chickweed, shepherd’s purse and purple deadnettle. So says Marilyn Thelen, Michigan State University (MSU) Extension educator.

“Weeds and alfalfa got an early start” in mid-March, says Thelen. “But cool weather and frost slowed the growth of the alfalfa. The weeds kept growing.”

Especially vulnerable are winterkill-thinned alfalfa fields. “Where thin areas exist, there is an opening for opportunistic grasses and broadleaf weeds to establish. First-cutting alfalfa quality will be decreased, and the drying time may be increased.”

The good news: After first cutting, winter annuals won’t be a problem. To improve yields in subsequent cuttings, however, growers will need to address weed problems, Thelen urges. She recommends the MSU Weed Control Guide and the IPM Pocket Guide for Weed Identification in Field Crops (E-3081).