Control of the Blue-Green Sharpshooter and Effects on the Spread of Pierce’s Disease of Grapevines1

Abstract

Dilute sprays of dimethoate applied at 1.8 to 2.5 kg AI/ha to peripheral strips of natural vegetation and to adjacent grapevines on the margins of vineyards in Napa Valley, CA, in early spring in 1974–76 greatly reduced the numbers of the Pierce’s disease (PD) vectors, Graphocephala atropunctata (Signoret), entering vineyards for 2 mo. Applications were timed to follow a sharp increase in G. atropunctata flight activity as estimated by yellow sticky trap catches. Reductions in the rate of spread of PD were generally apparent one year after spraying in moderately susceptible grape varieties. No decrease in the spread of PD was evident in the very susceptible varieties ‘Pinot Noir’ and ‘Pinot Chardonnay.’