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Managing potato leafhoppers in alfalfa

Keith Jarvi Published on 12 April 2011

Potato leafhoppers have the potential to hurt alfalfa every year. This is generally a second-cutting and third-cutting pest and has been more common recently.

These small (one-eighth-inch long), bright green, wedge-shaped insects may cause severe damage to alfalfa by injecting a toxin into the plant as they feed. This feeding results in a distinctive yellow or purple triangle shape at the tip of the leaf.

First-year, spring-planted alfalfa fields are particularly attractive to and vulnerable to potato leafhoppers, as are fields planted last year. In older fields, these insects are usually a problem on second and third cuttings.

Newly developed resistant varieties will protect from potato leafhoppers fairly well, but alfalfa in the seedling stage may still be damaged. All fields should still be scouted, as large numbers of leafhoppers may still cause a problem, even in resistant variety fields.

Treatment decisions are based on numbers captured by sweep net. A sweep net is the only reliable way to scout for potato leafhoppers. You don’t need a lot of leafhoppers to cause a problem.

Many insecticides are registered for control, and all will provide good results when applied properly.  FG

—From University of Nebraska – Lincoln Crop Watch newsletter

Keith Jarvi
Integrated Pest Management
University of Nebraska – Lincoln