ABSTRACT
The requirement of market of China in winter stimulates the development of a large greenhouse industry for the production of out of season cucumbers. However, plant diseases are still a major restricted factor in production of greenhouse cucumbers. For example, downy mildew, caused by Pseudoperonospora cubensis (Berk.&Curt.) Rostov. (N.V. Shetty et al, 2002) and Powdery mildew, caused by E. cucurbitacacearum Zheng et chen and S. cucurbitae(Jacz. )Z. Y Zhao, are major foliar diseases of greenhouse-grown cucumber (H.F. Li, et al, 2001). Concerns about food safety, environmental quality and pesticide resistance have dictated the need not only for diagnosis and controlling the diseases, but also for forecasting them correctly and providing preventive measures for planters, namely providing an early warning.
