Disease cycle
The pathogen overwinters as fungal fruiting structures (chasmothecia) on canes, fruits and leaves on the ground. In the spring, ascospores are released from the overwintering chasmothecia after a rainfall, and are carried to other grapevine tissues by the wind. The spores then germinate and cause primary infections. After the primary infection, fungus develops another type of spore conidia, which is spread by the wind to other plant parts where it causes secondary infections. The powdery mildew fungus unlike black rot or downy mildew doesn’t require free moister for its infection and disease development, but relative humidity between 40 and 100% and temperatures between 6 and 32 ° C. Therefore powdery mildew can cause problems on grapevines also when it is too dry for the other diseases to develop.
Disease cycleThe pathogen overwinters as fungal fruiting structures (chasmothecia) on canes, fruits and leaves on the ground. In the spring, ascospores are released from the overwintering chasmothecia after a rainfall, and are carried to other grapevine tissues by the wind. The spores then germinate and cause primary infections. After the primary infection, fungus develops another type of spore conidia, which is spread by the wind to other plant parts where it causes secondary infections. The powdery mildew fungus unlike black rot or downy mildew doesn’t require free moister for its infection and disease development, but relative humidity between 40 and 100% and temperatures between 6 and 32 ° C. Therefore powdery mildew can cause problems on grapevines also when it is too dry for the other diseases to develop.
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