Pseudoperonospora cubensis (downy mildew) is an aggressive fungal pathogen of
cucumber. In 2007, glasshouse experiments with organically grown cucumber
(´Airbus`, ´Juliandra`) were performed to investigate the effects of a climate strategy
“conventional” versus “dehumidified” on the development of the downy mildew
epidemic. In both climate strategies the commanding variable for ventilation is the
temperature; in the strategy “conventional” the established set point for ventilation is
22 °C, whereas in the climate strategy “dehumidified” the set point for ventilation
varies from 18 °C to 23.5 °C, depending on the humidity. The results show that the
climate “dehumidified” lowers the occurrence of downy mildew significantly
