How to Manage Pests

Pierce's disease

Pierce's disease infection begins as a drying or "scorching" of leaves. The leaves become slightly yellowed along the margins before drying, or the outer edge of a leaf may dry suddenly while still green. The woody portions of diseased canes are generally dry. Some or all of the fruit clusters may shrivel and dry up at any time following fruit set. Diseased vines become increasingly stunted over time and have fewer and shorter canes that produce dwarfed leaves and little usable fruit.

Identification | Life cycle

Solutions

Pierce's disease is spread to vines by sharpshooters from many alternate hosts for the disease including bermudagrass, blackberry, and willow. There is little spread from grape to grape. Control of sharpshooters is not effective, although removal of alternate hosts may help. Grape varieties vary in susceptibility. 'Sylvaner', 'Thompson Seedless', and 'Ruby Cabernet' are less susceptible than other varieties. Remove vines as they become unproductive and replant with less susceptible cultivars.