Potato Leafhoppers Get an Early Start in Alfalfa - UNL CropWatch, June 7, 2012
June 7, 2012
Potato leafhoppers have arrived early this year and are starting to injure alfalfa in many areas. These tiny, yellowish-green, wedge-shaped insects often blow in from the southeast in late spring through mid summer. They can stunt alfalfa growth and are especially damaging to new seedlings.
Potato Leafhopper Management in Alfalfa, NebGuide G1136
An early symptom of leafhopper damage is a triangular or V-shaped yellow or purple area at the tip of alfalfa leaves. 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.
Scouting and Management
Starting now, check fields at least weekly for leafhoppers before symptoms appear, watching for signs before symptoms appear and there is some degree of loss. If you detect leafhoppers early and they are still present, insecticides can kill them easily. You may need to spray a couple times, though, since leafhoppers can migrate from other fields and reinfect your sprayed field.
However, if your alfalfa already is yellow and stunted, do not spray. Instead, mow your alfalfa to remove affected plant tissue and stimulate new growth. Unmown plants might not grow much more all year, lowering yield and potentially leading to stand loss over winter. In fields seeded this spring, after mowing spray insecticide when regrowth begins to protect growth. In established fields, don’t spray automatically. Instead, scout new regrowth at least weekly for leafhoppers. If they reappear, use insecticides before much damage occurs.
Information on threshold levels and insecticides is available at local extension offices.
Extension Forage Specialist