First report of brown root rot caused by Pythium vexans on ramie in Hunan, China

Abstract

Ramie is an important natural fibre crop and a perennial herbaceous plant of the nettle family Urticaceae. In 2013, brown root rot disease was observed on ramie plants in Yuangjiang, Hunan Province, China. Symptoms included stunted plants, reduced number of ramets per plant, and brown to purple-black discolouration of the root. The pathogen was identified as Pythium vexans according to morphological features and sequence identity (99–100%) to the published data for internal transcribed spacer (ITS), 18S and 28S rDNA sequences. The pathogenicity was confirmed on healthy fibrous roots of seedlings and on detached storage roots under greenhouse conditions. To our knowledge, this is the first report of brown root rot disease caused by Pythium vexans on ramie.