Guide helps avoid Pierce's disease

Grape growers throughout the state concerned about Pierce's disease, the glassy-winged sharpshooter and how to keep this potentially deadly problem out of their vineyards will want a copy of a new field guide from the University of California.

Pierce's Disease is a concise and authoritative handbook on the disease, its spread and strategies for containing the problem. The publication is written by UC scientists on the forefront of the battle — Lucia Varela and Phil Phillips, area advisors with the UC Statewide Integrated Pest Management Project and Rhonda Smith, UC Cooperative Extension viticulture advisor for Sonoma County. Alexander Purcell, a UC Berkeley entomologist who has studied Pierce's disease in grapes for more than 20 years, is also a major contributor.

“Pierce's disease and the glassy-winged sharpshooter have made headlines because they pose real threats to California's $2.8 billion wine, table and raisin grape crops,” said W.R. Gomes, UC vice president of agriculture and natural resources. “This fully illustrated publication allows growers to recognize early symptoms of the disease, easily identify the insects that spread it and craft effective management strategies to reduce damage to their vineyards.”

Deadly bacterium

While Pierce's disease was first identified more than a century ago, it gained national attention after the glassy-winged sharpshooter — a fast-spreading and voracious feeder — began wreaking havoc about 1998 in the vineyards of Riverside County's Temecula region. More recently, the disease and the glassy-winged sharpshooter have been found in the San Joaquin Valley. Today, industry, government and the University are working together to keep the pest from Central and North Coast vineyards, while seeking a cure through research and field trials.

Pierce's disease is caused by a deadly bacterium, Xylellafastidiosa, that chokes off a grape plant's ability to pump water from the soil through its tissue (xylem) to leaves. Diseased vines become nonproductive and usually die within a year or two after infection. Currently, there is no known cure for Pierce's disease.

Vividly illustrated with 26 color photographs and four tables, the field guide examines the Pierce's disease problem in six major sections. Included are descriptions of Pierce's disease incidence in the different grape growing regions of the state; descriptions of the four major insect vectors that spread X fastidiosa; and the role that alternative host plants play as a reservoir of the bacteria. Also in Pierce's Disease is information on the pattern of spread in vineyards by different vectors; how to monitor these pests and a description of management strategies growers can adopt.

The 20-page publication produced by the UC Division of Agriculture and Natural Resources (ANR Publication 21600) is priced at $6 a copy, plus tax and shipping, with discounts available for purchases of 10 or more. Pierce's Disease is available at local UC Cooperative Extension offices, directly from ANR Communication Services (6701 San Pablo Avenue, 2nd Floor, Oakland, CA 94608-1239), or by phone (800-994-8849), fax (510-643-5470), and online at (

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