Bob Gilbertson, a University of California plant pathology professor, will have the podium Aug. 30 as he updates fellow researchers at the Ameircan Phytopathological Society's annual meeting about tomato yellow leaf curl virus in California.

The society deemed his presentation so important that they invited the press to dial in to an 11 a.m. conference call so they could listen and later ask questions.

In March, the destructive virus was detected in tomato plants and whiteflies from a greenhouse in California's Imperial Valley. Tomato yellow leaf curl virus is distributed primarily by the whitefly, Bemisia tabaci. It spreads quickly from plant to plant within minutes; especially if the whitefly population is high.

"This is undeniably the worst tomato virus there is," Gilbertson says. In other areas where the virus is present, yield losses as great as 100 percent have been reported. This disease poses a significant threat as California is one of the main producers of processing and fresh tomatoes in the United States.

The telltale sign of TYLCV is the yellowing and upward curling of the leaves. As the virus progresses, the plant becomes stunted and it causes the flowers of the tomato plants to die and fall off, rendering the plant unable to produce fruit.

The good news is that the whitefly that carries the virus does not do well in colder areas, such as in Northern California, the state's primary tomato growing area.

"This gives us hope that we have this under control, but when the worst tomato virus gets introduced in the California, it is a serious issue. We are fortunate that we caught it as soon as we did," Gilbertson says.

A flyer showing symptoms of the virus is available at

Check back to this Web site Monday afternoon, Aug. 30, to learn more about tomato yellow leaf curl virus and its prognosis in California.