Top 6 Winter Kill FactorsTop factors that could affect alfalfa plants leading to a winter kill
Stand Age: Older stands are more likely to winterkill than younger plants.
Soils with a pH above 6.6 are less likely to experience winter injury.
Soil fertility: Stands planted in soils with high natural fertility are less likely to experience winter injury than those with low fertility.
Variety: Alfalfa varieties with superior winter hardiness ratings and a high disease resistance index are less likely to experience winter injury.
Cutting Management: Harvest frequency and timing of fall cutting will affect alfalfa winter hardiness. The general trend shows that the shorter the interval between cuttings during the growing season, the greater risk of winter injury. An aggressive harvest schedule prevents the plant from storing carbohydrates in its root structure which it will need to maintain health as it regrows. Stands in which last cutting is taken between September 1 and middle of October are at greatest risk, as plants did not have enough time to accumulate adequate carbohydrate levels in the root system before winter.
Snow Cover: Snow provides insulation to the plants and the crown. The crucial temperature region is two to four inches below the soil surface where a large part of the root structure is located. Stands that have at least six inches of stubble left will be able to retain more snow cover and be less susceptible to winter injury.