Symptoms of Sclerotium rolsii on Cucurbitaceae

• Organs attacked :

 Sclerotium rolfsii attacks all organs of Cucurbitaceae located in or near the soil, whether the plants are very young (in nurseries) or adult in the field.

• Symptoms :
  • Mainly large, moist, soft lesions on fruits in contact with the ground (Figures 1 to 5). Their “skin” sometimes ends up splitting (figure 6). Eventually, the rot spreads to the internal tissues and whole fruits can decompose.
  • Damp and dark lesions on certain portions of stem in contact with the ground, evolving into rot (figure 7).
  • Collar lesions sometimes reported, gradually encircling it over several centimeters.
  • More or less reversible secondary foliar wilting that can lead to the drying out of plants.
  • Focus distribution of diseased plants.
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• Signs : dense whitish mycelium covering the damaged organs. Smooth structures, rather spherical (1 to 3 mm in diameter), initially white in color, then fawn to reddish brown, gradually visible within the mycelium: sclerotia resembling mustard seeds (figure 8).  

• Affected production areas :