Checking Alfalfa For Winter Injury

Extremely cold temperatures and the lack of insulating snow in many places this past winter could have a detrimental effect on alfalfa crops.

Dan Undersander is an Extension forage specialist at the University of Wisconsin. He says alfalfa buds form in the fall for first growth in the spring. If those buds are killed by the cold, the alfalfa plant has to start over forming new buds. This means yield is delayed, and sometimes reduced. You can check the health of your plants before they start to green up.

"When the frost is out a week or so of the ground, you can dig a few plants and in the top 6”, look at the quality of the taproot. If it’s turgid and off-white like a potato, then it’s a healthy plant," says Undersander. "If it’s showing signs of wilting, or a little bit ropey or brown, then it’s a dead or dying plant."

Once it starts greening up, let the alfalfa grow at least three-inches tall, and count the number of stems. Stems determine the density of the stand and the yield potential.

"Our recommendation is if you have greater than 55 stems per-square-foot, then you have the potential for the maximum yield, depending on the environment," says Undersander. "If you’re between 45 and 55 stems, then there will be some yield reduction, but it might be worth keeping if a lot of fields are in worse-case."

If you count below 40 stems, Undersander says there will be weed problems, reduced yield, and you’ll have to make replanting decisions.