The early open winter with sub zero temperatures, and then periods of ice and standing water on lower sections of the fields may be of concern for the potential for winterkill this spring. We will not know the severity of winterkill until the alfalfa greens up. Be sure to walk the fields and dig up plants to make the correct assessment of potential damage.
Stand assessment should be evaluated by looking at:
1. Are the plants alive? As soon as the frost comes out of the soil, dig up a few plants 4-6 inches deep and look at the condition of the tap root. If the root is firm or turgid, it is alive and healthy. If it is soft and browned like the photo, it is dead or dying.
2. Are there thin spots in the field? A healthy stand capable of maximum yields should have 55 stems/ft2. Regarding plant count, a high yielding alfalfa stand should have at least 20 plants/ft2. If stands are less than 12 plants/ft2, the crop should be rotated.
When can I reseed alfalfa into the same field?
1. For stands seeded in 2012 (less than 1 year old), fields can be disked and then reseeded immediately or no-till seeded with little risk of autotoxicity. Older stands should be rotated to another crop before reseeding.
What legume credits can I expect from the killed alfalfa?
2. For a stand that is more than 1 year old you can expect 150 lbs N/acre legume credit if there were at least 4 plants/ft2. For 2012 seeded alfalfa, legume credits would be about 90 lbs N/acre if top growth was not harvested and about 60 lbs if only stubble was left prior to winter.
The following is the Burrus/Hughes Alfalfa lineup which includes a Premium 214FY Brand Alfalfa as well as a the Hybrid 388HY Alfalfa:
Article courtesy of DowAgroSciences