Grey mould disease on tomato
The name, ‘grey mould’, describes the masses of grey spores produced on the rotted parts of plants affected by this fungal disease. The fungus involved is mainly a decomposer of dead plant tissue but it can invade living tissue as well, especially if the plants are unhealthy, and late in the growing season.
Any plant that has some dead tissue attached, such as withered flowers or leaves, can develop this disease. Old plants in cool, damp conditions are very susceptible. Most common in a wet season, it often affects soft fruit, french beans, celery, lettuce, cucumbers and tomatoes, but it is implicated in die-back of branches of gooseberries, skimmia, choisya and elaeagnus too.
Avoid damp air for indoor plants, especially in the dull months. Remove dead plant parts before they are invaded. Strawberry and raspberry fruits are often affected, especially in a wet summer, and more than half the crop can be lost. Remove the affected fruits as they are a source of infective spores. Balanced feeding with high potash reduces the problem.
Better air movement through the plants, growing strawberries on a raised drill and more thinning out of raspberries will give good control. If the cultural methods of control prove inadequate, spray at least twice, once when the first flowers open, with Systemic Fungicide and again when flowering has finished.