Myrothecium Leaf Spot -- Myrothecium roridum

January 1, 2004 - 01:00

Host:begonia, dieffenbachia, gloxinia, New Guinea impatiens, philodendron, spathiphyllum, pansy

Symptoms: Symptoms of Myrothecium leaf spot for the majority of host plants include spots anywhere on leaves. The spots initially appear water-soaked and are dark brown to black in color. Irregularly shaped black sporodochia can form with a white fringe of mycelium. These spore structures appear in concentric rings within the necrotic areas on the lower surface of the leaf.

Conditions Favoring Disease: This disease occurs during conditions with temperatures between 70° and 81°F, moisture on leaves and poor greenhouse sanitation. The fungus may invade plant tissue through open wounds most easily.
How Pathogen Survives/Disperses: The fungus survives in soil or plant debris. The optimum temperature for spore germination is 82°F.

Photo and write up provided by Syngenta Professional Products

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