Gummosis

Gummosis or scab (Cladosporium cucumerinum) is a serious disease of greenhouse cucumbers grown under wet and cool conditions. It can also affect other cucurbits.

Symptoms
Infected fruits develop sunken spots through which oozes an amber-like gum. A dark mould develops on the surface of the gum.

Treatment
Destroy all diseased fruit. Raise the temperature and reduce humidity.

Prevention
Maintain a warm, well ventilated environment for growing.