The effects of kaolin, harpin, and imidacloprid on development of Pierces disease in grape

• Author(s): Civerolo, Ed;
• Abstract: Incidence of Pierce's disease (PD), caused by the bacterium Xylella fastidiosa, continues to increase in many vineyards in California due to the establishment and spread of the vector Homalodisca coagulata (Say) (Glassy-winged sharpshooter). Commercially available materials [particle file (Surround WP) containing 95% kaolin, systemic acquired resistance inducer (Messenger) containing 3% harpin], and Admire 2F (imidacloprid) were evaluated in greenhouse and field experiments, for their effects on reducing X. fastidiosa transmission, and reducing X. fastidiosa infections and PD development. In the greenhouse tests, PD incidence was reduced by 30%, 42%, and 42% with Admire 2F, harpin and Surround WP, respectively. Treatment of grapevines with harpin, Surround WP, and Admire 2F reduced transmission of X. fastidiosa by 11%, 9%, and 11%, respectively, in treated grape plants maintained in the greenhouse. Infield studies, PD incidence was 6% in Surround WP treated plots and 14% in convential insecticide treated plots. PD development in harpin treated plots was 13%, 7%, and 6% when 160, 320, and 460 g harpin a.i./ha were used respectively. PD incidence in untreated control plants was 19%. harpin treated plants grew more vigorously than plants treated with Surround WP and Admire 2F, and untreated control plants. Higher GWSS mortality rates were observed on plants treated with Surround WP. Results from both greenhouse and field studies show that harpin, Surround WP, and Admire 2F would be useful in reducing transmission of X. fastidiosa by GWSS and in reducing infections and PD development.
• Publication Date: Jan 2007
• Journal: Crop Protection