Abstract
Biological mode of action of fluazinam (Frowncide®) against clubroot of Chinese cabbage was studied. Germination of resting spores was inhibited in a suspension by fluazinam application at 1ppm or more. Root hair infection decreased when the soil was inoculated with resting spores previously incubated in a suspension with fluazinam. Both root hair infection and club formation were greatly inhibited in the presence of fluazinam in the inoculated soil. Fluazinam inhibited club formation when working in the soil until the stage of root hair infection, whereas it had no effect after cortex infection. These results suggest that fluazinam possesses fungicidal action to resting spores and inhibits root hair infection and cortex infection, thereby leading to the inhibition of club formation.
