Don’t rush to replant a winter-injured alfalfa stand, advises Stephen Barnhart, forage specialist for Iowa State University Extension.
Although they’re often slow to recover in spring, winter-damaged plants might survive satisfactorily, says Barnhart. “A quick decision to destroy a winter-injured stand is not recommended.”
Wait to assess a stand until the alfalfa is 3-4” high. Consider the number of plants per square foot and the age of the stand, he says. Because crown and root diseases also affect legume stands, check for dead, dying or diseased crown and root tissue.
Randomly select at least one 1-square-foot area for every five to 10 acres and dig up all of the plants in the area. Inspect new growth, including the crown and buds, to determine if the tissue is still alive. Count the number of live plants per square foot and use the table below to rate the stand.
Split the taproots and evaluate their general health, too, Barnhart advises. The core of a healthy taproot is firm and creamy white, while damaged or dying taproots are yellowish brown to chocolate brown and watery or dry and fibrous in texture. Only healthy plants will contribute significantly to yield. So if a plant’s taproots are more than 50% diseased, don’t keep it as part of the stand count.
Barnhart suggests the following management strategies after completing stand evaluation:
- If stands are winter-injured but will be harvested this season, allow plants to mature to 10-25% bloom or later before cutting.
- Increase cutting height to 3-4”.
- Maintain good fertilizer and insect management.
- If stands are severely winter-injured and significant losses likely, plan to re-establish a new hayfield this spring.
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