The disease is a severe boll rot. Initially, localized spots appear and progressively coalesce to cover the whole cotton boll.
Infected tissues turn almost black.
Phytophthora boehmeriae was isolated from diseased plants. Colony morphology, growth rate, features of asexual and sexual structures, maximum growth temperatures were examined. The pathogenicity of the Greek isolates was confirmed by artificial inoculation of detached cotton bolls. In addition, the analysis of a-esterase isozyme revealed a unique pattern for P. boehmeriae when compared to P. cactorum and P. parasitica . This fungus is also reported to cause brown rot on citrus fruits in Argentina, root rot of Pinus patula in Australia, and cotton boll rot in China.