Sclerotinia Stem Rot Caused by Sclerotinia sclerotiorum on Soybeans in Nigeria. C. N. Akem, Grain Legume Improvement Program, International Institute of Tropical Agriculture, Oyo Road, PMB 5320, Ibadan, Nigeria. K. E. Dashiell, Grain Legume Improvement Program, International Institute of Tropical Agriculture, Oyo Road, PMB 5320, Ibadan, Nigeria. Plant Dis. 76:101. Accepted for publication 7 May 1991. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0101C.
Sclerotinia sclerotiorum (Lib.) de Bary (syn. = Whetzelinia sclerotiorum (Lib.) Korf & Dumont) was isolated from cultivars of soybean (Glycine max (L.) Merr.) in a breeding nursery trial at BukufU, near Jos in the state of Plateau, Nigeria, in August 1990. Severely infected plants of breeding lines TGx 1440-IE and TGx 1627-3F were observed at growth stages R2 and R3 in two isolated locations in a 5-ha field. Symptoms included wilting, withering, and yellowing of leaves. Withered leaves were necrotic, tattered, and curled but remained attached. Lesions about 15-20 cm long, encompassing the entire stem, were also observed. Lesions were covered with "cottony" white mycelium, especially near the soil line. Black sclerotia, 3-5 mm long and of varying shapes, were observed on the lesion surface. Tissues with lesions were readily shredded when teased to observe pith cavity. Oblong sclerotia, 5-10 mm long, were present in the pith of severely infected stems. S. sclerotiorum was isolated on acidified (pH 5.8) potato-dextrose agar by plating both surface-sterilized stem segments of diseased plants and sclerotia from the surface and pith of infected stems. Koch's postulates were satisfied using whole plants and detached shoots (l). To our knowledge, this is the first report of Sclerotinia stem rot of soybean in Nigeria and in West Africa. Reference: (1) H. A. Melouk and C. N. Akem. Proc. Am. Peanut Res. Educ. Soc. 18:57, 1986.