Check Alfalfa Fields Now For Winterkill

Badger View

Many farmers across Wisconsin are discovering their alfalfa winterkilled.

Published on: May 3, 2013

Now that alfalfa is finally beginning to green up after the winter that would not end, many farmers across Wisconsin are discovering that their alfalfa winterkilled or is suffering significant winter injury.

Dr. Dan Undersander, University of Wisconsin Extension forage agronomist, says he has been getting reports that damage varies from low spots only in fields to major portions of alfalfa fields.

Short of plowing up all of your alfalfa fields and starting over, what can be done?

Undersander recommends first that you make sure dead spots are actually dead and not just delayed. He says, dig a few plants and check the top 4 inches of the taproot for color and if the root is soft and mushy or hard. Ideally, Undersander says, the taproot should be off white, like the inside of a potato. If alfalfa roots are off white and hard, they are alive and just delayed. Also, check fields that are putting out small shoots. Sometimes dying alfalfa plants will produce shoots 1 to 2 inches tall and then die, he notes. Again, dig a few plants and look for off-white, hard taproots.

Dont delay checking your alfalfa fields for winterkill or winter injury. The sooner you assess the damage, the sooner you can determine what to do. Photo by Mike Rankin
Don't delay checking your alfalfa fields for winterkill or winter injury. The sooner you assess the damage, the sooner you can determine what to do. Photo by Mike Rankin

Next, he says, determine what percentage of the field is affected. If it is just a small percentage of the field, go over the affected areas with a drill as soon as possible and seed 10 pounds of a 50/50 mix of Italian (annual) ryegrass and perennial ryegrass per acre. If a moderate percentage of the field is winterkilled, Undersander recommends interseeding 10 pounds of Italian ryegrass as soon as possible, harvest first cutting and then plant corn for maximum yield.

If a major portion of the field or the entire field is winterkilled, then Undersander suggests seeding an emergency forage crop of oats and peas as soon as possible. He recommends seeding two bushels of oats along with 20 pounds of peas per acre. After harvesting, this can be followed with corn for silage or BMR sorghum-sudangrass for silage or baleage.

Of those options, he says corn will likely produce the most tonnage of any forage, but if you are concerned we will have another hot, dry summer like last year, sorghum-sudan grass is a good choice.

Alfalfa can also be seeded into a different field at 10 to 12 pounds per acre along with 6 pounds of tall fescue and two pounds of Italian ryegrass per acre. Or, alfalfa can be seeded with two bushels of oats and 20 pounds of peas per acre. Ryegrass or oats and peas will maximize production in the seeding year.