Be Alert to Risk of Alfalfa Winter Injury

Be Alert to Risk of Alfalfa Winter Injury February 17, 2017

Like many alfalfa growers this year, I’m a little worried about what this winter may do to our alfalfa fields.

Alfalfa usually is a dependable crop. It seems to come back year after year. After the nice winters. After the cold winters. And even after the ugly winters. But what about this winter?

I’m not good at predictions and I’m not going to tell you that your alfalfa will be fine this spring nor will I predict that it winterkilled, but I will suggest that you check it extra closely this spring to judge how well it made it through this winter.

The recent long spell of daytime temperatures in the 50s, 60s, and even some 70s probably awakened at least some alfalfa plants from winter dormancy. When alfalfa plants break winter dormancy they use nutrients stored in their roots and crown and start to grow as if spring has arrived.

A return to average winter temperatures forces these plants back into dormancy. Another streak of warm weather could break dormancy again, using more nutrient reserves. If this is followed by more cold weather, eventually the alfalfa plants will exhaust their reserves and be unable to start growing when spring truly does return.

Another problem in other areas has been snow followed by melting followed by freezing. Prolonged or repeated formation of ice at or on the soil surface can prevent the exchange of gases between the air and the soil. As alfalfa roots respire during winter they produce some gases that can become toxic to alfalfa plants if too concentrated. The roots also need some oxygen to respire and remain healthy. Without this interchange plants can essentially suffocate.

It’s impossible to predict if alfalfa will be hurt this winter. Since weather conditions have been risky, be ready to check your fields and make any necessary adjustments early.

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