The best control for winter annuals is a thick, healthy alfalfa stand. However, as first cutting approaches, we see established alfalfa stands that were good going into the fall, now have a lot of weed pressure from winter annuals. Common culprits are common chickweed,shepherd’s purse and purple deadnettle.

Winter annuals were established in the fall, overwintered in the vegetative state and began growing in mid-March during the early warm spell. This spring, alfalfa broke dormancy early – MSU Extension News’ Regional reports on Michigan field crops – March 15, 2012 showed a picture in southwest Michigan of alfalfa greening up on March 14. Both weeds and alfalfa got an early start, but cool weather and frost slowed the growth of the alfalfa. The weeds kept growing. Fields where alfalfa suffered winter kill came into spring with a thin stand and were not able to out compete the weeds. As a result, these fields have a weed problem.

The good news is that after first cutting, the winter annuals will not be a problem. However, 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 due to the weeds.

To improve the yield in subsequent cuttings, weeds will need to be controlled. Refer toMSU Weed Control Guide for specific recommendations.

For more information on weed control questions, visit MSU field crops weed control specialist Christy Sprague’s website.

MSU’s weed control group has developed an excellent tool for identification of Michigan weed species. You can view the IPM Pocket Guide for Weed Identification in Field Crop (E-3081) or purchase it from the MSUE Bookstore.