Abstract: ObjectiveThe objective of this project is to study the effects of climate factors on the germi-nation and survival of grape downy mildew sporangia,and provide the theoretical basis to control the disease.MethodThe survival and germination of sporangium was researched by controlling temperature,humidity, light and other climatic factors.ResultThe results showed that sporangia could germinate in water and re-lease zoospores,and the optimum germination temperature was approximately 1 8 -22℃.Sporangia survival was related to temperature,humidity,and light.At 35℃and relative humidity of either 70;or 100;,spo-rangia died within three days.Sporangia survived for more than six days at 10-20℃,regardless of light con-ditions.Disease was observed when these shriveled sporangia were inoculated onto leaf discs.This indicated that shriveled sporangia cannot be used as an indicator whether the sporangia were dead or not.Sporangia were dead after illumination with 0.58 ×102μW /cm2 of ultraviolet light for 5 h.The sporangium did not germi-nate and was not pathogenic after exposure to 8 h direct light.The sporangium survived with 10 h irradiance of scattered light.ConclusionSporangia could germinate in water and release zoospores,and the optimum ger-mination temperature is about to 18 -22℃;the sporangium was sensitive to ultraviolet light.At the direct light intensity of 65,000-107,100 lx,the sporangium would die in 8 hours.