California growers are on alert for a new viral disease, tomato yellow leaf curl, which has the potential to devastate the state's tomato production. The first California discovery of the virus was in Brawley during March of this year.

The disease belongs to a family of viruses known as geminiviruses and is spread by whiteflies or leafhoppers. Symptoms of infected tomato plants include stunted and abnormal upright growth, and small crumpled leaves that show strong yellowing (chlorosis). Flowers on infected plants commonly fall off before fruit set, dramatically reducing production. Heavily infected fields could be a total loss.

"Because this disease is potentially devastating for tomato production in California, it is critical to limit its spread," said UC Davis plant pathology professor Robert Gilbertson.

State officials with the California Department of Food and Agriculture have contained the initial outbreak of tomato yellow leaf curl, and a monitoring program is in effect in commercial fields, retail stores and backyard gardens in Southern California.

A UC Integrated Pest Management Project brochure, which contains information about the disease and the white fly that caries it, is available online at http://www.ipm.ucdavis.edu/PMG/r783103311.html. The California Tomato Growers Association is sending a copy of the brochure to each tomato grower in the state.