47th TWC, Tob. Work. Conf., 2016, abstr. 41

Effect of fatty alcohol concentration and formulation on mechanical transmission of bacterial wilt at harvest

Clemson University, Florence SC USA

Bacterial wilt disease caused by Ralstonia solanacearum continues to be a serious impediment to the successful production of flue-cured tobacco in the southeast U.S.A. Mechanical transmission of the bacterium during leaf removal plays a significant role in the spread and severity of the disease. As a multi-pass mechanical harvester removes infected leaves in the field, the bacterium contaminates defoliators, gleaners and leaf guides. These contaminated harvester components then transfer the bacterium to adjacent healthy plants. Previous modifications to the harvester design reduced stem injury and transmission of the bacterium. The replacement of stationary rubber leaf guides with a continuous rubber belt system showed less stem bruising and reduced mechanical transmission and infection of stalk tissues in replicated field studies. The objective of the present trial was to evaluate the use of the continuous rubber belt system in combination with C8 + C10 and C10 fatty alcohols on the mechanical transmission of R. solanacearum during harvest. Plants (K196) were grown under standard agronomic practices. Plots consisted of rows 15.2 m long with a 1.2 m row spacing. Experimental design was a randomized complete block with four replications and repeated in time. Inoculation was performed by misting harvester defoliators and gleaners with a bacterial suspension before harvesting individual rows. Fatty alcohol concentrations and formulations were 4, 8 and 16% of C8 + C10 (1 octanol and 1 decanol mixture, Off Shoot T EC) or C10 (N-decanol, Antak EC). The continuous belt system alone reduced mechanical transmission of R. solanacearum over the stationary leaf guide. Application of Off Shoot T EC and Antak EC significantly reduced the disease index and stem necrosis (P = 0.05) over the belt alone and the stationary leaf guide. (Reprinted with permission)