Archives Alfalfa selection and cold tolerance Alfalfa Variety Performance Information in Minnesota gives the best assessment on alfalfa variety. The WSI was developed from winter survival tests conducted at Arlington and Landcaster, Wisconsin and Rosemont and Morris, Minnesota.
Plants are seeded and stressed during the seeding year and rated for winter survival.
This index determines a variety s winter hardiness. Improved disease, insect, and nematode resistances have enhanced winter survival in many new alfalfa varieties. However, resistance to cold temperatures is still the most important factor in determining varietal winter hardiness in northern latitudes. The overwintering behavior of alfalfa is under complex genetic and environmental control, and breeders are just now beginning to understand how to combine fast recovery and high yield potential with resistance to severe cold temperature stress. In general, the older an alfalfa stand, the more susceptible it will be to winter injury.