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Wait to Clip Drought-Stressed Alfalfa (06/08/17)

Many parts of the state where alfalfa is grown are experiencing moderate to severe drought, which is causing spring alfalfa growth to wilt and shoots and leaves to dry.

Wait to Clip Drought-Stressed Alfalfa

Many parts of the state where alfalfa is grown are berti.1 2experiencing moderate to severe drought, which is causing spring alfalfa growth to wilt and shoots and leaves to dry. During drought, forage is likely in short supply and farmers are likely to try to get as much forage as possible. But harvest timing decisions are important to keep a healthy and productive alfalfa stand.

Alfalfa is a perennial crop, and keeping it perennial is important to have forage in the future. Whenever alfalfa plants are stressed, their response is to replenish the root and crown reserves (sugars, proteins) as soon as possible. Reserves are vital to support new growth from the buds in the crown once soil moisture is available.

The lowest roots reserves occur when the plant is 6 to 8 inches tall in the spring before the first cut. Reserves are replenished about the time the plant blooms.

Drought-stressed alfalfa will flower early when still very short. The plant is accelerating its life cycle in an attempt to produce seed in the event that drought stress continues and the mother plant dies. If drought persists, alfalfa will drop its leaves and go dormant until conditions improve. Alfalfa is well-adapted to survive a drought when managed correctly to avoid additional stresses on the plant.

The big question for producers is whether to clip/mow droughty alfalfa. Clipping drought-stressed alfalfa will not help the plant regrow faster when rainfall or moisture comes back. If stands are not 12 to 15 inches tall orberti.3 4 yield is not enough to cover the cost of harvest, producers should leave the alfalfa uncut until rain falls and the alfalfa’s dormancy is broken.

Clipping or harvesting droughty-alfalfa at 6 to 8 inches would cause additional stress on the plant, reducing future regrowth and possibly causing plant death.

Remember, the root reserves are at the lowest at 6 to8 inches, so do not clip or mow alfalfa if shorter than 12 to 15 inches.

A common concern for farmers is that if the alfalfa flowers and never reaches 12 to 15 inches, will it flower again this year? The answer is yes. If it rains and soil moisture conditions improve, buds in the alfalfa crown will grow new shoots. If soil moisture is available, the shoots will grow to a normal height for a second cut (18 to 22 inches). Then your harvest stage should be the 10 percent bloom stage to keep high-quality hay.

Avoiding any additional stresses on the plant, such nutrient deficiency or insect and diseases, is important. Producers should fertilize with phosphorus and potassium if they have not done so and their soil test indicates fertilization is needed. Potassium (potash) is particularly important because this nutrient helps the plant mobilize sugars back to the root to tolerate the drought stress. Also, when soil moisture is replenished, alfalfa will have all the nutrients it needs to resume a vigorous growth.

 Marisol Berti

NDSU Plant Science Professor, Forage and Biomass Crops

 

Ellen Crawford

Editor, NDSU Agriculture Communication

This site is supported in part by the Crop Protection and Pest Management Program [grant no. 2017-70006-27144/accession 1013592] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed are those of the website author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

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