Symptoms of Didymella on Squash

• Organs attacked :

• Symptoms :
  • Lack of germination, death of seedlings. Wet, dark spots may develop on cotyledons (figure 1 and 15), stems, and cause seedling death.
  • Oily to livid leaf spots. Rather circular in shape, they expand as they evolve, take on a brown tint, become necrotic and dry out (figure 3). Note that they can be located at the edge of the limb initially, and that a yellow halo sometimes surrounds them.
  • Initially limited, moist and dark lesions initiating on fruits at random (figures 5 to 10, from more or less senescent floral parts, at the level of the stylar zone, from micro wounds (peduncular zone). Large lesions can start on contact with the ground (figures 11 to 14) Irregular in shape, they spread and gradually darken, the flesh takes on a blackish hue.
  • Presence of brown exudates on fruits.

•  Signs : Presence of tiny and numerous brown to black globular masses on the lesions. These are the fruiting bodies of this fungus: perithecia and pycnidia visible under a magnifying glass (figures 15 and 16).
• Possible confusion :
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• Production areas affected :