This stunted and yellow alfalfa field was affected by very high potato leafhopper numbers and drought.
Newly developed alfalfa varieties with resistance can provide fairly good protection from potato leafhoppers. But large numbers of the pest in a stand can still cause problems, warns Robin Wright, entomologist with University of Nebraska-Lincoln (UNL) Extension.
“All fields, including resistant variety fields, should still be scouted,” he says.
Potato leafhoppers are about 1/8” long, bright green and wedge-shaped. The insects can cause severe damage to alfalfa by injecting toxin into plants as they feed. The feeding results in a distinctive yellow or purple triangle shape at the leaf tip.
“First-year, spring-planted alfalfa fields are particularly attractive to and vulnerable to potato leafhoppers, as are fields planted last year,” says Wright. “In older fields, these insects are usually a problem on second and third cuttings.”
Using a sweep net is the only way to reliably scout for potato leafhoppers. For help in making treatment decisions, he recommends UNL’s Potato Leafhopper Management In Alfalfa.
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