Main symptoms

 

On melons, Athelia rolfsii attacks almost mainly fruits that come into contact with the soil. A wet lesion develops on the part of the melons touching the ground. It quickly evolves into a moist, soft rot, and spreads to internal tissues. Eventually the “skin” of the melon splits.

If the climatic conditions and / or the soil are sufficiently humid, a dense whitish mycelium  covers the diseased tissues. Smooth, rather spherical structures (1 to 3 mm in diameter), first white in color, then tawny to reddish brown, are gradually visible within the mycelium: these are the sclerotia of Athelia rolfsii . The latter have an appearance comparable to mustard seeds. Eventually, the fruits can rot completely.

lesions Collar are sometimes reported, gradually girdling it over several centimeters. Affected tissues are moist and turn brown more or less intensely. Subsequently, the fungus also invades the roots which it causes to rot.

Remember that this fungus grows particularly on young plants with tender tissues. It would therefore not be surprising to see some attacks in the nursery and in the weeks following planting, especially if the conditions at the time are hot and humid.

Diseased plants generally have a distribution in foci . In some particularly humid areas, the mycelium spreads on the ground to pass from one plant to another.