Plants Are Resistant to Deadly Pierce’s Disease

Original Post:ucdavis.edu/food/news/uc-davis-releases-five-new-wine-grape-varieties

For the first time since the 1980s, University of California, Davis, researchers have released new varieties of wine grapes. The five new varieties, three red and two white, are highly resistant to Pierce’s disease, which costs California grape growers more than $100 million a year. The new, traditionally bred varieties also produce high-quality fruit and wine.

“People that have tasted the wine made from these varieties are extremely excited,” said Andrew Walker, geneticist and professor of viticulture and enology at UC Davis, who developed the new Pierce’s disease resistant varieties. “They are impressed that they’re resistant but also that they make good wine.”

Pierce’s disease a growing threat

Pierce’s disease is caused by a bacterium spread by a group of insects called sharpshooters. It causes grapevine leaves to yellow or “scorch” and drop from the vine. The grape clusters also dehydrate, and infected vines soon die. While the disease has been around since the beginning of wine grape production in California, concerns have escalated with the arrival of the nonnative glassy-winged sharpshooter, which has the potential to spread the disease more rapidly. Pierce’s disease occurs most often near rivers and creeks, and around urban and rural landscaping where sharpshooter populations reside.

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