PHYTOPHTHORA BOEHMERIAE BOLL ROT - A NEW THREAT TO COTTON CULTIVATIONIN THE MEDITERRANEAN REGION

A boil rot of cotton (Gossypium hirsutum L.) was observed for the firs t time in Greece in August 1993 in Larissa and Volos counties, and in August and September 1995 in Trikala and Phthiotis counties. Fungi of the genus Phytophthora were isolated from diseased plants. Morphologic al characteristics of the pathogen were recorded on mounts made direct ly from the infected tissues or after growth of the isolated fungus on corn meal agar or sterile distilled water. Colony morphology, growth rates, features of asexual and sexual structures and maximum growth te mperatures were examined. A Phytophthora species new to Europe, Phytop hthora boehmeriae Sawada, attacking cotton bells, was identified. The pathogenicity of the isolates was confirmed by artificial inoculations of detached cotton bells. Analysis of cr-esterase isozymes revealed u nique banding patterns for isolates of P. boehmeriae compared with tho se of P. cactorum and P. parasitica, which are Phytophthora species wi th similar morphology.