This 4-page factsheet details the findings of a project undertaken to study greenhouse cucumber diseases and their causes and to develop effective management strategies. The most important diseases detected across Australia were root rot, stem rot and wilt, which frequently caused one third of plants to die prematurely. This premature wilting and dying is referred to as “damping off” and the fungal pathogens that cause it may occur individually or as a combination. Environmental conditions and crop hygiene play an important role in the incidence and severity of “damping off” losses. The main fungi that cause “damping off” are Pythium, Phytophthora, Fusarium and Rhizoctonia. The plant symptoms, the source of the fungi, how these organisms spread and the management strategies for controlling damping off are described. There are no chemicals (excluding soil fumigants) currently registered for controlling these pathogens. The management strategies emphasise cultural methods of preventing the diseases.