Grey mould is an extremely common fungus and grows on many plants. As the name suggests a greyish fuzzy fungal growth develops over the infected area. The spread of the growth will vary depending on the stage to which the infection has developed.
Other than the grey fuzzy fungal growth, look out for extensive discolouration with leaves or fruits turning brown and bleached white spots on plant petals.
Treatment and control
General tips: Remove and destroy all affected plant parts. Under glass increase ventilation. Fungicides containing myclobutanil, sulphur or penconazole may give some incidental help.