Mark McCaslin and Tim Woodward
Container.........Bench, flat,or pot deep enough to allow root
Location ........Transplant 8-12 week old plants to
the field in late May or early June; direct seeding with
hand thinning also acceptable
Nurseries should be intensively managed in the establishment year. They should be clipped at early to mid bud stage with a final clipping in mid September in MN or WI. Under this cutting regime the plant enters the winter in a stressed condition, allowing for more consistent winter injury in moderate winters. Local experience will provide information on which clipping dates provide the greatest separation among varieties.
1 No injury ...Plant has uniform, symmetrical appearance, all shoots are about equal in length .
2 Some injury ..... The plant is symmetrical, but regrowth is slightly uneven
3 Significant injury . Regrowth varies in length, reduced vigor
4 Severe injury .... Plant has sparse shoots, regrowth is very irregular, poor vigor
5 Dead plant
An average score (ASI) can be calculated for each cultivar. A winter survival rating (1-6) can be assigned based on the ASI relative to the standard check cultivars.
A successful test must show a significant difference (p=.95) between the class 2 and class 4 check cultivars. The class 6 checks must have an ASI of 4.6 or higher.
Care should be taken to read the winter survival test
after all the plants have broken dormancy. Readings taken
too early may underestimate winter survival in some
Degree of severity of this test may be increased by snow removal (2).
3. Peterson, M, D. Barnes, W. Knipe, M. McCaslin, J. Moutray, D. Viands, and T. Woodward. 1989. A
seven location study of the relationship between fall
dormancy and winterhardiness in alfalfa. Proc. 21st
Central Alfalfa Imp. Conf. p22-23.