Two types of powdery mildew often appear side by side on vines: downy mildew and powdery mildew. The first symptoms of downy mildew of the vine Plasmopara viticola appear on the upper side of the leaves as irregular pale green spots.In conditions of high air humidity on the underside of the leaves, at the spot of the spots, you can see a gray-white coating of the stems with spores.
As the disease progresses, necrotic dark yellow spots appear on the upper leaves, especially along the main veins. Then, the affected leaves fall prematurely, which increases the susceptibility of the bushes to frost.
If the inflorescences become infected, they may die and fail to bundle their fruit.Infected fruits turn brown and ripen faster, and then rot.Bushes weakened by the disease bear fruit of inferior quality, which may be manifested by the sour taste of the wine obtained from them.
Disease progresses better when there is excessive rainfall at temperatures around 15-18 ° C.The prevention of downy mildew is the removal of fallen leaves, pruning properly and combating weeds that growing near shrubs, they increase air humidity.
A chemical plant protection product can also be used.The preparation should be applied immediately before the formation of inflorescences, just before flowering, when the fruit is the size of a pea.Further treatments are carried out as needed during chronic rainfall.
All-season vine care
Powdery mildew Uncinula necator manifests itself as a white powdery coating that can appear on both sides of the leaf blade.The symptoms of powdery mildew appear as early as May, but the greatest severity of this disease is observed in summer, when heavily affected leaves dry up and fall off the bush.Mycelium can also appear on fruits that develop and they dry up.
Comparing the harmfulness of these two diseases, downy mildew is more dangerous for grapevines.Powdery mildew does not require high air humidity and water for spore germination for its development. dry years, he may be a greater threat.
