PREVIOUS studies have indicated the importance of infected seed as a source of the stem and fruit rot disease of tomatoes caused by Didymella lycopersici Kleb. Hickman1 reported 25-34 per cent infection of an outdoor crop grown from seed, a proportion of which was infected. Schoevers2 demonstrated the presence of mycelium and pycnidia of the fungus on the seed coat and radicle of germinating seed, and Ogilvie3 observed the fungus on the cotyledons and hypocotyl of tomato seedlings.