BACTERIAL WILT OF PERILLA CAUSED BY PSEUDOMONAS-SOLANACEARUM AND ITS TRANSMISSION

In Taiwan, a wilt disease of perilla (Perilla crispa) was caused by Pseudomonas solanacearum race 1, biovar 3. Strains from perilla were pathogenic to solanaceous and other hosts, but strains from solanaceous and other hosts were not pathogenic to perilla. Stem inoculations of perilla plants with P. solanacearum resulted in 90-100% wilting, but perilla plants rarely wilted when planted in infested soil. However, various population levels of P. solanacearum were detected in roots of 88% and in stems of 76% of asymptomatic plants grown in infested soil. The pathogen was mechanically transmitted from a wilted plant to healthy plants. The symptomless carriers also served as an inoculum source for the spread of the pathogen to healthy perilla plants. Leaves of perilla are harvested periodically during the growing season by mechanical means, resulting in a high incidence of the disease.