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An early symptom of leafhopper damage is a triangular or V shaped yellow or purple area at the tip of an alfalfa leaf. This discoloration is caused by a toxin the leafhopper injects into the alfalfa plant as it sucks out plant juices. As feeding continues, the entire plant can turn yellow and growth may stop.
Starting now, check fields at least weekly for leafhoppers before symptoms appear. If you detect leafhoppers early and they are still present, insecticides can kill them easily. Unfortunately, you may need to spray several times since leafhoppers can migrate from other fields and reinfect your sprayed field.
If your alfalfa already is yellow and stunted, do not spray. Instead, first mow your alfalfa to remove poisoned plant tissue and to stimulate new growth. Unmown plants might not grow any more all year, lowering yield and potentially leading to stand loss over winter. After mowing new seedlings, spray insecticide after regrowth begins to improve growth. But don't automatically spray established stands. Instead, closely scout new regrowth at least weekly for leafhoppers. If they reappear, then use insecticides before much damage occurs.
Bruce Anderson
Extension Forage Specialist
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| Published by University of Nebraska-Lincoln Extension in the Institute of Agriculture and Natural Resources Cooperating with the counties and the U.S. Department of Agriculture. | ||
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