CORESTA Congress, Shanghai, 2008, AP 32

Reduced mechanical transmission of Ralstonia solanacearum using a modified harvester and C10 fatty alcohol as a disinfectant

Clemson University, Dept. of Entomology Soils and Plant Sciences, Pee Dee REC, Florence, SC, USA

Mechanization both in leaf (multipass harvester) and flower (topping) removal has contributed to the spread and severity of bacterial wilt in North and South Carolina. When a mechanical harvester removes an infected leaf the bacterium can contaminate defoliators, gleaners and leaf guides. The contaminated harvester components can then move the bacterium to adjacent healthy plants increasing the severity of disease. A single pass of a multipass harvester removing the bottom 4 leaves increased the % plant infection over a non-harvested control from 9 and 2% to 69 and 47% for K 326 and K 346, respectively (P = 0.001). The objective of the present trial was to evaluate a modified harvester designed for the ability to reduce stem injury and the application of disinfectants to prevent the transmission of the bacterium to healthy stem or leaf scars. Stationary rubber leaf guides on the multipass harvester were replaced with a continuous rubber belt that moved with the stem as the harvester moved down the row. Tobacco stalks contained less stem bruising and reduced mechanical transmission and infection of stalk tissues when a continuous belt replaced stationary leaf guides. Percent plant infection declined from 64 and 51% to 39 and 34%, for K 326 and K 346, respectively when a continuous belt replaced the stationary leaf guides ( P = 0.02). The use of a disinfectant (C10 fatty alcohol) applied during the harvesting process to leaf defoliators reduced stem necrosis from 2.4 to 1.4 on a 0-5 scale ( P = 0.04). The use of an integrated control system to control bacterial wilt will be discussed.