Impact
The aster or six-spotted leafhopper, Macrosteles quadrilineatus, does not injure the plant directly. However, certain phytoplasma-like potato disease agents are transmitted by this insect pest in the San Luis Valley.

The potato leafhopper has not been found in the San Luis Valley. However, the intermountain potato leafhopper, which produces small flecking wounds on leaves, may occur.

Description and Symptoms

Leafhoppers are elongated, wedge-shaped insects, broadest in the head and thoracic regions and tapering along their wings. They are strong fliers and may migrate long distances.

The aster leafhopper's body is dull light green and may appear silvery gray when wings are folded at rest. Six distinct spots occur on the top of the head.

The aster leafhopper is the principal vector of aster yellows or purple top, a disease caused by a bacteria (phytoplasm).

Adults are best sampled by sweep net, and nymphs by examining randomly picked midplant leaves. Nymphs are rarely seen on potatoes in the San Luis Valley.

Several leafhoppers occur in the San Luis Valley, most of which are harmless to potatoes.

Integrated Management

Scout by taking 100 sweeps across two rows with a net 15 inches in diameter. Check for the presence of adult leafhjppers, which transmit disease organisms. Adults have six dark spots on the head.

Apply pesticides only to control large infestations which rarely occur. Pesticide application is only economically viable on seed potatoes.

This material is based on work supported by the San Luis Valley Water Quality Demonstration Project Best Management Practices Advisory Committee, Colorado State University Cooperative Extension, Farm Service Agency, Natural Resources Conservation Service, and the U.S. Department of Agriculture under authorization as 1991 U.S. Department of Agriculture Water Quality Demonstration Project.