Rhizoctonia Web Blight -- Rhizoctonia spp.

January 1, 2004 - 01:00

Host: Pittosporum, foliage plants, and many other plants including vinca and impatiens.

Symptoms: Rhizoctonia web blight first appears as lesions on the leaves just above the soil surface and in the center of the plant canopy. The spots can either expand (quickly killing the entire leaf) or remain as restricted lesions. Hyphae of the causal organism develop extensively during high humidity, forming webs that can cause abscised necrotic leaves to remain attached to the plant shoots.

Conditions Favoring Disease: High humidity, particularly in the plant canopy, and hot temperatures favor disease development.

How Pathogen Survives/Disperses: Sclerotial or hyphal propagules can be disseminated to foliage by splashing water or handling. The fungus can grow readily along the soil surface from plant to plant during propagation.

Photo and write up provided by Syngenta Professional Products

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