Powdery mildew is caused by an ascomycete fungus by the Erysiphales. This is manifested as a whitish mycelium visible to the naked eye. The fungus converva in the remains of vegetation affected and diffuses through conidia. Optimum conditions for disease development with a temperature of 20-25 ° C and 50-70% the relative humedad.
Powdery mildew can attack any part of the vine:
1) Leaves: Symptoms can appear in both the beam and the underside, in both cases a white ashen dust usually observed, they may be limited to certain areas, or occupy the entire surface of the sheet.
- When the clusters become visible (phenological state F), with the majority of outbreaks among 5 and 10 cm.
- At the beginning of flowering (I start phenological).
- With granos pea-sized Garbanzo.
- At the beginning of veraison (5-10% grains changing color).