But now the culprits have been found in a trap at a vineyard near San Francisco, at farms near Fresno, and at two nurseries near Napa, home of the nation's premier wineries. When glassy-winged sharpshooters bite into a grapevine, they infect it with the bacterium Xyella fastidiosa. The pathogen produces a gummy substance, clogging the vine's vascular system and shutting off the flow of water and nutrients. Unlike native sharpshooters that infect vines planted near stream banks, the newcomers fly long distances, breed in the state's abundant citrus orchards, and eat voraciously. The invaders feed not on new vine growth that can be pruned away, as native sharpshooters do, but on the vine's main stem, destroying the plant's life-sustaining system.
Infected vines become reservoirs for the bacteria.
Scientists hope to map the bacterium's genome to find ways to make the vines resistant to it. One insecticide is being used, and small wasps, which lay their eggs on those of the glassy-winged sharpshooter, may be bred to try to lower reproduction. World Report Inc. All rights reserved.