Damping-off of Some Cucurbitaceous Crops in Saudi Arabia with Reference to Control Methods

Isolation of seed borne fungi from sweet melon (najed and red Queen varieties) and vegetable marrow (squash) using PDA, Plain agar media and blotters revealed the presence of Alternaria alternata (Fr.) Keissler, Fusarium semitectum var,majus from Najed melon, A. alternata (Fr.) Keissler, F. sambucinum Fuckel from Red Queen melon and A. chlamydospora Mouchacca, Cephalosporium sp., and F. oxysporum schlecht from squash. Pathogenicity tests showed, that all these fungi were highly pathogenic on their respective hosts. The optimum temperature for its growth ranged from 25–30°C and the optimum pH was 6.0. In pot trials, seed dressing with Banrot, Bavistin and Topsin-M at the rate of 4 g/kg seed was superior in controlling the damping-off of melon and squash. These fungicides were effective in inhibiting mycelial growth, spore germination and development of the isolated fungi. Hot water treatment at 55 C/20 min or solar heating (av. 37°C) for 90 min were next to fungicides.