Disease Note

Ascochyta Blight on Major Food Crops in Rwanda, East Africa. M. Price, Institut des Sciences Agronomique du Rwanda, B.P. 629, Kigali, Rwanda. D. Cishahayo, Institut des Sciences Agronomique du Rwanda, B.P. 629, Kigali, Rwanda. Plant Dis. 70:1159. Accepted for publication 3 September 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-1159a.

In 1983, Ascochyta blight (A. phaseolorum Sacc.) caused severe damage on several varieties of cowpea (Vigna unguiculata (L.) Walp.) in Rwanda. In 1985, an intensive survey identified A. phaseolorum on leaves of beans (Phaseolus vulgaris L.) and soybeans (Glycine max (L.) Merr.), A. adzamethica Schoschiaschuili on leaves of groundnuts (peanuts) (Arachis hypogaea L.), A. bataticola Chochr. & Djurin on leaves of sweet potatoes (Ipomoea batatas (L.) Lam.), and A. pisi Lib. on leaves of peas (Pisum sativum L.). All fungal identifications were confirmed by the Commonwealth Mycological Institute. Ascochyta blight on cowpea produced a circular to irregular-shaped, zonated brown lesion with a chlorotic halo. Lesion size varied according to susceptibility of crop. The disease also caused severe defoliation, then death of susceptible plants. This is the first report of Ascochyta blight of sweet potato, cowpea, soybean, and pea in Rwanda.