AGRONOMY NOTES 04/10/03 7:48:52 AM
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Potential Alfalfa Winter Injury
As winter begins to release us from it's grasp our thoughts are turning toward our many spring tasks. The planter is rescued from the back of the shed, the tractors get their spring tune-ups, and our final field preps are made. While you are busy doing all this stuff, remember to monitor those precious alfalfa stands. When I talk about monitoring, I mean getting out in the field and scouting the overall health of the crown area in several parts of the field. A healthy crown is white in color and firm when you try to squeeze it. If the crown appears slightly yellow or tan and has a water logged appearance, it's on the down-hill slide. If the crown and root area look like the picture to the right, it's as good as dead. The plant can survive with varying degrees of crown rot, but the greater percentage of the crown and root affected, the lower the production and survivability of the plant.
As you all know, a good snow cover can provide much needed insulation for a perrenial like alfalfa. Generally, a 4" to 6" blanket of snow is most effective, and even 2" has a great benefit. This being the case, there wasnt' a field in our trade territory that had such protection. Typically, early fall regrowth following last cutting can also provide insulating protection. But we also had many late cuttings taken last fall, which left little chance for good regrowth. When you couple an open winter with later harvesting you can see that the winter injury risk is elevated this spring. Despite these facts, before you write off your alfalfa keep in mind that drier soils are working in our favor. When you talk about alfalfa damage, drier soils are safer than wet or water logged dirt. With these thoughts in mind, here is a list of things to consider when assessing your alfalfa.
- Damage is most likely on older stands (2-4 yrs) or on acres where fertility programs have been marginal.
- Stands which were cut mid September to mid October before a killing frost did not accumulate adequate carbohydrate reserves in the fall. This will affect spring growth and first cutting yield; and may result in stand decline.
- Winter injury will not be as severe in areas with >2" of snow cover or where temps stayed over 15 degrees.
-Stand damage can also occur with an early spring break in dormancy followed by colder temps.
The agronomy staff at United Farmers Coop encourages you to give us a call to help you monitor those alfalfa stands. We have the expertise and resources to assist you in evaluating your options when a stand is marginal or aging. As a full service dealer we are always available for your use. Alfalfa is a high dollar crop that requires as much attention as your corn and soybeans. If we haven't been called out to your alfalfa acres yet, ask yourself one question - Why not? To calculate your own risk of winter injury, click here for a handy worksheet that will help you score your stand.
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