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.
*Use restricted to certified applicators only.
|Insecticide||Rate of application|
|*Ambush 2E||3.2 to 12.8 oz|
|*Baythroid 2||0.8 to 1.6 oz|
|Dimethoate 400||0.5 to 1 pt|
|*Furadan 4F||1 pt|
|Imidan 70WP||1.33 lb|
|Lorsban 4E||0.5 to 1 pt|
|malathion 57%EC||1.5 to 2.25 pt|
|*Penncap-M||2 to 3 pt|
|*Pounce 3.2EC||4 to 8 oz|
|Sevin XLR Plus||2 pt|
Kevin Steffey, Extension Entomology, (217) 333-6652