Potato leafhoppers have arrived in parts of Nebraska, and growers should establish scouting programs to protect their alfalfa, advises Bruce Anderson.
The tiny, yellowish-green, wedge-shaped insects often blow into the state from the Southeast from late spring through midsummer, says the University of Nebraska Extension forage specialist. They stunt crop growth, turn alfalfa yellow and “especially hurt new seedlings.”
An early symptom of leafhopper damage is a triangular or V-shaped yellow or purple area at the tip of alfalfa leaves, caused by toxins that leafhoppers inject as they suck out plant juices. As feeding continues, entire plants can turn yellow and growth may stop.
Check fields at least weekly for leafhoppers before symptoms appear, Anderson says. “If detected early, insecticides can control leafhoppers. You may need to spray a couple times, though, since leafhoppers can migrate from other fields and re-infect your sprayed field.”
Don’t spray if alfalfa is already yellow and stunted. Instead, mow the crop to remove affected plants and stimulate new growth. Plants left unmowed may not grow much more all year, lowering yield and potentially leading to stand loss over winter.
After mowing new seedings, Anderson recommends spraying insecticide when regrowth begins. “Don’t automatically spray established stands. Instead, scout new regrowth at least weekly for leafhoppers. If they reappear, use insecticides before much damage occurs.”