Three fungal diseases; damping‐off, powdery mildew and Choanephora fruit rot, were found to occur on vegetable marrow throughout the year, in the southern region of Oman (Dhofar), causing considerable damage. The percentage of infection of damping‐off was reduced by seed dressing, using Fernasan D (25% thiram + 20% gamma‐HCH) at a rate of 3 g/kg seeds. Seven fungicides were used to control both powdery mildew and Choanephora fruit rot. Benomyl, thiabendazole, ethirimol and dinocap were highly effective against powdery mildew. Mancozeb, dinocap and thiabendazole reduced the infection of Choanephora fruit rot.