University of Illinois

No. 11/June 6, 1997

Potato Leafhoppers Deserve Attention

We have received reports of potato leafhoppers at or above threshold levels in some fields of alfalfa. Dave Mowers, Mowers Soil Testing Plus, Inc., has observed as many as two leafhoppers per net sweep. This density is at the threshold level for alfalfa that is 12 inches or taller. Obviously, if leafhoppers are at or above threshold level and the alfalfa has not been cut, the best strategy is to cut the alfalfa, then keep a close eye on the regrowth. Harvest will cause adult leafhoppers to fly to other fields and will kill many nymphs. However, as other fields of alfalfa are cut, adult leafhoppers will move back into fields of regrowing alfalfa. Tender, regrowing alfalfa is very susceptible to leafhopper feeding injury (the threshold for regrowing alfalfa 3 inches or less in height is 0.2 per sweep).

Insecticides suggested for control of potato leafhoppers in alfalfa are presented in Table 4. Please follow all label directions and precautions.

Table 4. Suggested insecticides for control of potato leafhoppers in alfalfa.

InsecticideRate of application
*Ambush 2E3.2 to 12.8 oz
*Baythroid 20.8 to 1.6 oz
Dimethoate 4000.5 to 1 pt
*Furadan 4F1 pt
Imidan 70WP1.33 lb
Lorsban 4E0.5 to 1 pt
malathion 57%EC1.5 to 2.25 pt
*Penncap-M2 to 3 pt
*Pounce 3.2EC4 to 8 oz
Sevin XLR Plus2 pt
*Use restricted to certified applicators only.

Kevin Steffey, Extension Entomology, (217) 333-6652