Temecula Valley grape growers recently learned that a disease-carrying leafhopper that threatens area vineyards is not just a local problem anymore. Pierce's Disease wiped out 40,000 acres of vineyards and 50 wineries in the Anaheim area a century ago.
Infected plants die because water-conducting vessels in infected plants are blocked.
Although little is known about the leafhopper that spreads the disease, university experts warned that steps need to be taken now to minimize the disease's impact. Unlike its related species found in other parts of the state, the glassy-winged sharpshooter is larger and can fly greater distances. This means it can infect plants farther away from its host plant, typically citrus crops. As a result, the disease has spread throughout Temecula vineyards, not just along the edges as is the case in other regions. Scientists are assessing ways to limit infestations, including a promising ground-applied insecticide, severe pruning of vines, and chemicals that attack the bacterium.