First Report of Leaf Anthracnose Caused by Colletotrichum alatae on Water Yam (Dioscorea alata) in China

Abstract

Water yam (Dioscorea alata [Dioscoreaceae]) is a vegetatively propagated tuberous food crop cultivated widely in the tropics and subtropics (Mignouna et al., 2003). It is the most widely distributed species of yam in China and eaten mainly as a vegetable. During July 2016, anthracnose-like lesions were observed on the leaves of cultivar Da56 at a plantation in Danzhou City, Hainan Province. Leaf symptoms began as small, brown, pinpoint spots ＜1 mm in diameter and enlarged to dark brown to almost black, irregular blotches ＞10 mm diameter with yellow haloes. Approximately 35% of the plants showed the same symptoms on their lower leaves. Symptomatic leaves were collected randomly from different parts of the field. Tissue was removed from the margin of three lesions per leaf. It was then surface sterilized in 75% ethanol, air-dried, plated on potato dextrose agar plates (PDA) and incubated at 28℃ and a 12-h photoperiod. Colonies with similar characteristics were produced after 4 days. Four isolates (DA1605-16...