Leaf spots were first observed on watermelon (Citrullus vulgaris Schrad) under polyethylene film-covered greenhouse in November 2002. Symptoms appeared as dark-brown circles or large irregular spots on the leaves of watermelon. Occasionally, zonal gro...
Leaf spots were first observed on watermelon (Citrullus vulgaris Schrad) under polyethylene film-covered greenhouse in November 2002. Symptoms appeared as dark-brown circles or large irregular spots on the leaves of watermelon. Occasionally, zonal growth of the lesions was observed. Under humid conditions, small black sclerotium-like bodies (sporodochia) were produced on the surface of the lesions. The sporodochia on leaf lesions were sessile, polymorphic, variable in size, 35-850 ㎛ in diameter, and 30-470 ㎛ in depth. Conidia in sporodochium were black in mass, one-celled, rod-shaped, with rounded ends, hyaline, guttulate, and measured 6-8×1.6-2.2 ㎛ in size. The pathogen was identified as Myrothecium roridum Tode ex Fr. This is the first report of Myrothecium leaf spot on watermelon naturally occurring in commercial greenhouses.