Potato leafhopper, Empoasca fabae, injury is being found on susceptible trees in many parts of Illinois. Potato leafhoppers attack many landscape trees, including maple, crabapple, birch, and ash. Red maples are extremely susceptible, whereas silver, sugar, and Norway maples are more tolerant if not stressed from improper watering, fertility, or mulching.
Potato leafhoppers have piercing-sucking mouthparts. Feeding within the vascular tissues of plants, they inject a toxic fluid. Feeding, especially on maples, results in stunted tree shoots and leaves that curl downward, with brown edges. Symptoms resemble phenoxy herbicide (for example, 2, 4-D or dicamba) injury. On other plants, such as ash, feeding by potato leafhoppers creates small, white or yellow spots on leaves, resulting in a stippled appearance because potato leafhoppers, like spider mites, remove the chlorophyll from leaves. Potato leafhoppers don't overwinter in Illinois because their eggs are sensitive to cold. They winter in the Gulf of Mexico and are blown into Illinois by prevailing winds from early May to early June.
Adults settle into alfalfa fields during early spring migration; after the first cutting of alfalfa, they migrate in large numbers onto ornamental plants. Adults are small (about 1/8-inch long), wedge-shaped, and pale green, with white eyes. Females lay eggs into the veins on the underside of leaves. The eggs hatch in 6 to 9 days into light green nymphs that are found on leaf undersides. The nymphs tend to move sideways when disturbed; they undergo five instars before molting into adults. Adults and nymphs are similar, except that adults are larger, have wings, and can fly. The wings are held rooflike over the body. Empty, white, cast skins on the underside of leaves provide evidence of potato leafhopper activity. There may be three to five generations per year in Illinois.
Pest-control materials must be applied before potato leafhoppers cause plant damage. Control can be obtained with pyrethroid-class pest-control materials, such as bifenthrin (Talstar), cyfluthrin (Tempo), lambda-cyhalothrin (Scimitar), and permethrin (Astro). If damage has already occurred, applying pest-control materials prevents further damage, and new growth will appear normal beyond the damaged leaves. Regular scouting helps minimize the potential for severe foliar damage.