Black rot and downy mildew of grape are both apparently of American origin on wild species of grape. Importation of Phylloxera-resistant American rootstocks into France spread the causal fungi of these diseases into Europe. Black rot is now found in most all countries where grapes are grown and where the climate is cool and wet. Black rot is of little importance in California because of the arid and warm climate.
KeywordsDowny Mildew Concentric Zonation Fall Leave Primary Inoculum Biological Specialization
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