Alfalfa Variety Selection

*Extension Crop Specialist, Professor of Forage Genetics and Research Associate in Forages, respectively, Department of Plant & Soil Sciences, Montana State University, Bozeman, MT 59717 Alfalfa—the most productive and most widely adapted forage species—is indeed “Queen of the Forages.” A grower’s initial decision to produce alfalfa and subsequent choice of varieties have long-term consequences. There are over 200 alfalfa varieties available in the northern USA and Canada, and this number increases by 30 to 40 new varieties each year. Alfalfa varieties should be chosen on the basis of winter hardiness, yield potential, pest resistance, persistence, forage quality and availability. Montana has variety performance trials in major irrigated and dryland hay production areas. Performance summaries are published annually and are available to Extension agents, growers and seed companies. “Recommended” varieties have been widely tested in Montana for a minimum of three years at four locations. Obviously, local information should be used by growers to narrow down the list of potential varieties. The final step is to choose a reputable local seed supplier. In most cases, the seed companies have a complete lineup of alfalfa varieties, as well as additional performance information and recommendations. Winter hardiness In most areas of the northern US and Canada, winter hardiness is the key factor influencing stand longevity and forage yield. Alfalfa varieties are classified depending upon how rapidly they become dormant in late summer. Early fall-dormant varieties are more winter-hardy than nondormant varieties; thus earliness of fall dormancy has historically been used as a measure of winter hardiness. Very dormant varieties (fall dormancy class 1) such as ‘Ladak 65’ have heavy first cut yields but have very little fall growth. Very nondormant varieties (fall dormancy class 9) produced in the desert southwestern USA continue growth late into the fall and can be harvested nine or ten times per year. Varieties in fall dormancy classes 1 through 4 are suitable for production in Montana. On large farms, it is advisable to split acreage between varieties differing in fall dormancy. Less dormant varieties generally have faster recovery and higher yield potential, but are more susceptible to winter injury. The more dormant varieties typically mature later, but persist better for long-term stands.