A3723-E GUniversityARDEN of Wisconsin–ExtensionFACTS Potato Leafhopper

K.A. Delahaut

In Wisconsin, the potato leafhop- The first symptom of injury is a per ( fabae) is a seri- brown, triangular lesion on the tip ous annual pest of snap of the leaflet. As symptoms devel- and potatoes. Damage caused op, lesions spread backward and by includes stunted inward from the margin, eventual- plants, brown and ly destroying the entire . The reduced plant vigor. burned appearance of the foliage is the source of the term “hopper- A wide range of plants serve as burn.” Plants become stunted hosts for the potato leafhopper. and yellow and leaves curl Potato leafhopper adults These include , , all upward. Premature death of the types of beans, , dahlia, plant may occur in severe eggplant, potatoes, rhubarb, soy- infestations. beans, strawberries and other bedding plants. Injury develops most rapidly dur- ing hot, dry weather. Appearance Unfortunately, yield loss often The potato leafhopper is a small occurs even before the develop- 1 ( ⁄8-inch), bright green, wedge- ment of obvious symptoms. shaped with whitish spots Though plants may show little evi- on its head and thorax (upper dence of hopperburn, yield loss- body). Leafhoppers have pierc- es can be substantial. ing-sucking mouth parts and Life cycle Potato leafhopper nymph jump, fly or crawl when disturbed. Nymphs appear similar to adults Potato leafhoppers blow into but lack fully developed wings. Wisconsin each spring on southerly winds; they do not over- Symptoms and effects winter in the state. Large leafhop- Both adults and nymphs feed by per populations migrate from inserting their mouth parts into alfalfa fields in June and early the plant’s vascular tissue and July causing their numbers to extracting sap. Damage results seemingly “explode” overnight. when vascular tissue is blocked, Adult females insert their white permanently reducing the plant’s eggs into the stems or large leaf photosynthetic efficiency. veins of susceptible crops. Each GARDEN FACTS University of Wisconsin– Extension female lays approximately 3 eggs Commercial vegetable growers tations are more likely to occur in each day for about a month. should use a sweepnet to monitor crops planted adjacent to alfalfa Nymphs hatch 7–10 days later their fields. Take 25 sweeps with fields. If leafhopper populations and molt 5 times over a period of an insect sweepnet per sample exceed the accepted action 12–15 days before turning into site. Use at least 5 sample sites thresholds, insecticides provide adults. There are typically 2 gen- per 30 acres. To monitor small the only effective means of con- erations per year in Wisconsin, gardens or farms, carefully turn trolling them. Many foliar insecti- and populations decline signifi- over 25 leaves and count the cides used for other pests pro- cantly in August. nymphs and adults on the leaves. vide excellent control for potato Select leaves from the middle leafhoppers. Refer to the Scouting suggestions portion of the plant. University of Wisconsin–Extension Snap beans and potatoes should Control publication Commercial be scouted regularly for leafhop- Vegetable Production in per activity. Leafhoppers tend to Healthy plants withstand damage Wisconsin (A3422) for recom- migrate into other crops in early more effectively than stressed mended insecticides or contact summer after alfalfa is cut. This is plants. Irrigation and cultural your local county Extension the key time to watch for early practices that favor the crop are agent. migrants in vegetable plantings. recommended. Leafhopper infes-

Action threshold levels for vegetables Life stage Seedling snap beans Larger snap beans Potatoes

1 Nymphs 1 every 10 leaves 1 every 10 leaves 2 ⁄2 every 25 leaves

1 1 Adults ⁄2 adult per sweep 1 adult per sweep ⁄2-1 adult per sweep

When to scout for potato leafhopper April May June July August September early mid late early mid late early mid late early mid late early mid late early mid late Potatoes Beans

Author: K.A. Delahaut is an outreach specialist with the Integrated Pest Management Program at the University of Wisconsin–Madison and the University of Wisconsin–Extension, Cooperative Extension. Thanks to Jeff Wyman and Phil Pellitteri for reviewing this information. Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, University of Wisconsin–Extension, Cooperative Extension. University of Wisconsin–Extension provides equal opportunities in employment and programming, including Title IX and ADA requirements. If you need this information in an alternative format, contact the Office of Equal Opportunity and Diversity Programs or call Extension Publishing at (608) 262-2655. © 2001 by the Board of Regents of the University of Wisconsin System. Send inquiries about copyright permission to: Director, Cooperative Extension Publishing, 201 Hiram Smith Hall, 1545 Observatory Dr., Madison, WI 53706. To see more Cooperative Extension publications, visit our web site: www.uwex.edu/ces/pubs/ Potato Leafhopper (A3723-E) I-04/2001