Symptoms of mildew on zucchini

• Organs attacked :

• Symptoms :
  • Initially moist, oily spots, yellowing and gradually becoming necrotic (figures 1 to 3).
  • The spots are rather small (a few millimeters in diameter), especially angular because they are delimited by the veins, which gives the blade a mosaic appearance (figures 4 and 5).
  • When climatic conditions are humid, the spots spread rapidly and some coalesce leading to necrosis and drying out of certain sectors of the lamina (figure 6).
  • Symptoms progress rapidly on leaves, plants and sometimes in plots.

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• Signs : presence of felting on the underside of the limb whose color varies from light gray to dark mauve. This felting is rather difficult to observe on zucchini given the small size of the lesions (figures 7 and 8).
• Possible confusion :

• Production areas affected :