50 years ago, scientists ID’d a threat to California wine country

Excerpt from the June 29, 1974 issue of Science News

a red and black sharpshooter insect sits on a plant

When glassy-winged sharpshooters (one shown) latch onto a healthy grapevine, they can transmit the bacterium that causes Pierce's disease. The infection prevents the plant from getting water and nutrients, and it eventually dies.

Heather Broccard-Bell/iStock/Getty Images Plus

Sweet discovery for the wine industryScience News, June 29, 1974

Pierce’s disease remains a problem for California grape growers.… [Pathologists] have identified the cause of the disease. They were able to isolate a small, non-motile, rod-shaped bacterium which is probably a new species and therefore as yet unnamed.


Pierce’s disease still vexes California vineyards and is estimated to cost the state more than $100 million per year. But researchers now know more about the culprit: Xylella fastidiosa.

The bacterium spreads among grapevines via insects, specifically sharpshooter leafhoppers and spittlebugs. When the insects suck sap from an infected plant, they pick up the microbe, which harmlessly multiplies in their mouths. Leafhoppers and ­spittlebugs then transmit the pathogen to vines when they latch onto a healthy plant. The subsequent infection prevents water and nutrients from flowing into the plant, eventually killing it.

There’s still no treatment for Pierce’s disease. Perhaps one day it will be possible to genetically engineer domesticated grapevines to be resistant to the bacteria.

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