The effect of Powdery Mildew in the vineyard
Spores of powdery mildew are transmitted from vine to vine by the wind. If left untreated, they will go dormant in the bark during winter and reemerge during the rains of early spring when temperatures reach 50 degrees Fahrenheit. Early rain will spread powdery mildew from the bark of previously infected vines to new growth.
Sulfur and fungicides are used to treat outbreaks of this scourge. Sulfur is really only effective later in the growing season during warm, dry weather. This is because rain will wash sulfur off of the vines. It is important that any sulfur treatments are closely monitored. Too much can burn leaves and stunt growth, especially with certain varietals.
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