Long-term effects of winterkill in alfalfa fields include reduced yields and shorter stand life.
By: Phil Kaatz, Michigan State University Extension
Reports from the Thumb of Michigan about alfalfa fields that were thinned from last winter continue to reinforce the challenge of keeping high producing alfalfa in rotation. Fields that were late to emerge from dormancy have had reduced yields. By adding the challenge of a wet spring and a lack of good drying weather for dry hay, you can understand the sense of frustration with the weather for hay producers. For the fields that were hurt by the winter, producers should carefully assess whether the current alfalfa stands will be adequate for subsequent years.
Many alfalfa growers are preparing to seed new fields and with some of the best varieties in short supply; producers should contact their seed suppliers early to insure they can get the variety they want. Michigan State University Extension recommends that a summer seeding should be planted by Aug. 1 for the northern regions of Michigan and before Aug. 15 for the southern regions. Varieties grown in Michigan should be at least moderately winterhardy, high yielding, and have resistance to diseases such as bacterial wilt, anthracnose and Phytophthora root rot. For long-term stands, varieties should be winterhardy for best results.
Producers can access the yield results for varieties grown in Michigan at the 2013 Michigan Forage Variety Test Report. Fields selected for summer seeding should have been rotated out of alfalfa for one year to reduce the potential for alfalfa toxicity.
Best results for alfalfa establishment are achieved when a firm, weed-free seedbed is utilized. Seeds should be planted shallow at a depth of 0.25 inches for fine-textured soils and 0.5 inches below the surface for coarse-textured soils. For fields that are planted to a pure alfalfa stand, 15-18 pounds of seed are recommended.