Ascochyta Blight: A Growing Problem In Common Bean

This seed-borne disease seems to be spreading in South Africa, and is also more virulent than in earlier years. Fortunately, fungicides are available to deal with the problem.

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In South Africa, ascochyta blight was reported only briefly during the 1980s in Mpumalanga, the Eastern Cape and KwaZulu-Natal. More recently, the disease has been observed often at the Agricultural Research Council’s Cedara Research Station near Pietermaritzburg in KwaZulu-Natal. Both the incidence and severity of the disease appear to be increasing.

Ascochyta blight of the common bean (Phaseolus vulgaris) is a seed-borne disease caused by the fungus Phoma exigua var exigua. It occurs worldwide and can result in severe yield loss.

Cool to moderately cool temperatures (between 16°C and 24°C), high humidity, and rainy and misty weather favour the onset and development of symptoms. The pathogen becomes active at about 30°C.

SYMPTOMS