Stem rot of heading cabbage, a new symptom of cabbage Pythium rot, caused by Pythium ultimum var. ultimum.

Abstract

Severe stem rot of cabbage (Brassica oleracea L.) in heading stage has been observed in Gunma Prefecture, Japan since 2004. The causal agent was identified as Pythium ultimum Trow var. ultimum, a pathogen of Pythium rot of cabbage, based on morphological properties and rDNA-ITS sequence. When cabbage stems were inoculated with the isolates, the symptom of disease was reproduced, and the fungus was reisolated from the plants. To our knowledge, this is the first report of stem rot of cabbage in heading stage caused by P. ultimum var. ultimum. We propose adding stem rot as the new symptom of Pythium rot of cabbage.