山茱萸褐斑病病原鉴定

Identification of the causal agent of dogwood brown spots

山茱萸（Comus officinalis）为山茱萸科（Comaceae）山茱萸属植物，其成熟干燥果肉（俗称枣皮）为我国常用名贵中药材。河南省南阳市（西峡、内乡和南召等县）为我国山茱萸主产区之一，仅西峡县截止1990年已发展到500万株，年产枣皮315万埏，产值达4200万元，居全国首位。近年，作者对西峡县山茱萸产区进行病害调查时发现，由链格孢菌（Alternaria sp．）引起的山茱萸褐斑病发生普遍，该病严重发生时可致植株95％以上叶片枯死，落果率高达87％，造成山茱萸大幅减产，给当地果农带来严重经济损失。迄今，未见链格孢菌引起的山茱萸病害报道。本研究对该病的病原菌进行分离鉴定，以期为病害的防控提供依据。

Dogwood is a valuable medicinal plant. Nanyang of Henan Province, is one of the main dogwood- producing areas in China. In recent years, Dogwood brown spots severely occurred in Nanyang. The leaf brown spots were divided into I- and R-types based on their distinctive symptoms. Five Alternaria sp. isolates from disease leaves were collected. Two representative isolates （A18 and A16） were identified as the members of Alternaria alternata based on their morphological characteristics and ribosomal DNA internal transcribed spacer （rDNA-ITS） sequences after their pathogenicity on dogwood leaves was confirmed. This is the first report of A. alternata causing brown spot disease on dogwood.