Alfalfa winter survival in spring of 2009

Dan Undersander

Alfalfa stands have come through the winter in varying conditions depending on previous management and the locally occurring weather conditions this past winter. Generally survival was good but significant loss has occurred in central Illinois (due to heaving), Southwestern Wisconsin and Northeastern Iowa and Quebec. Most of the kill was a combination of snow melting to form ice and either the ice itself or lack of snow insulation during periods of cold caused injury and kill.

Winterkill and injury was generally worse where a late fall cutting had been taken. While late fall cutting is generally a recommended practice with more winterhardy varieties, it does increase risk of winterkill and this past winter is an example of that. Many cooperatives report much less fertilizer sold last fall. To the extent that potassium was not replaced, this would have increased winterkill.

Some northern sites are still seeing some small plants just beginning to grow in fields. If plants have healthy crowns, these small plants likely represent death of buds formed last fall. These injured plants will yield slightly less on first cutting (because they have to regrow new buds) but the plants should grown and contribute to the stand for the remainder of the season.

Many fields have suffered alfalfa loss in low spots as is common. However, where the dead spots exceed 30% of the land area, replanting should be considered. Alfalfa cannot be replanted into the spots due to autotoxicity. Recommendations would be red clover (6 lb/a), 50/50 mixture of Italian and perennial ryegrass (10 lbs of mixture/acre) or orchardgrass (8 lb/a) or tall fescue (12 lb/a). The latter two will yield slightly less this year but will survive and yield next year. 

The problem with interseeding is that the drying rate of the interseeded species is different than alfalfa. Thus, when making haylage or hay (especially) some portions of the field will dry differently than other portions. This often leads either to high alfalfa leaf loss or to moldy spots in hay. Fields with large dead areas (more than 25%) should be targeted for turn down.