Damping-off of Broccoli Seedlings Caused by Pythium megalacanthum in Japan

Abstract

Broccoli plug seedlings in Kagawa Prefecture, Japan, in 2014 and 2015, wilted and damped-off. A microorganism was isolated from stems of the diseased plants and identified as Pythium megalacanthum by morphological and molecular phylogenetic analysis. When the microorganism was inoculated onto broccoli plug seedlings, it produced identical symptoms to the original infection and the microorganism inoculated was re-isolated from the diseased plants. Thus, the causative pathogen was identified as P. megalacanthum. This is the first report of broccoli disease caused by this microorganism in Japan.