Symptoms of Sclerotinia sclerotiorum on Compositae

• Organs attacked :

• Symptoms :
  • Wet alterations, light brown color affecting the parts of the plants in contact with the ground and in particular the senescent leaves, then the collar (figures 1 and 2). thereafter, rot generalizing to the strata of leaves close to the ground (figure 3).
  • Petioles and main veins as well as the collar are invaded, which leads to chlorosis and wilting of the outer leaves (figure 4), then of the plants.
  • The rot affects all the leaf tissues which decompose and collapse (figures ). Uprooting these plants offers no resistance.
  • Spots starting on upper leaves exposed to ascospores; they quickly evolve into rot which gains many leaves and apples.

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• Signs : more or less fluffy and white mycelium  on all affected tissues (figure 2), as well as large irregular black structures, sclerotia which are  rather elongated, measuring 2-20 mm x 3-7 (figures 5 and 6). Small “trumpets”, apothecia, forming on the larger sclerotia.
• Possible confusion : Sclerotium rolfsii , Rhizoctonia solani  aerial,

• Affected production areas :