Crop & Pest Report


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Scout for Potato Leafhoppers in Beans (07/18/19)

Potato leafhoppers are migratory insects that are blown into ND.

Potato leafhoppers are migratory insects that are blown into ND. Economic populations of potato leafhoppers have been observed in dry beans near Tower City, Cass/Barnes Counties. The adult is small, about ⅛ inch long, wedge-shaped and pale green. Adults are very active, jumping or flying when disturbed. Nymphs are wingless. Both adults and nymphs will run backwards or sideways rapidly. Nymphs usually complete their growth on the leaf where they hatched, feeding on the underside of the leaf. Damage by leafhoppers is referred to as ‘hopperburn.’ Foliage becomes dwarfed, crinkled, and curled. Small triangular brown areas appear at the tips of leaves, gradually spreading around the entire leaf margin.

Both nymphs (immatures) and adults cause crop damage and should be counted when field scouting. The threshold for basing spray decisions is:

Dry beans - one leafhopper (adults + nymphs) per trifoliate leaf for later stages  

Soybeans -  5 leafhoppers (adults + nymphs) per plant in the vegetative stages

9 leafhoppers (adults + nymphs) per plant in early bloom stages

A treatment should be considered when visible injury symptoms are combined with large leafhopper populations.

Do not let infestations and damage progress to the point that yellowing of foliage is easily detected, because damage and yield loss has already occurred. Immediate treatment reduces further damage and protects new growth.

For insecticides registered for potato leafhopper control, please consult the 2019 North Dakota Field Crop Insect Management Guide E1143


Janet J. Knodel

Extension Entomologist

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