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Host Specificity of Nigerian and North American Isolates of Corynespora cassiicola. P. T. Onesirosan, Department of Plant Pathology, University of Wisconsin, Madison 53706, Present address of senior author: Plant Science Dept., University of Ife, Ile-Ife, Nigeria; D. C. Arny(2), and R. D. Durbin(3). (2)(3)Department of Plant Pathology, University of Wisconsin, Madison 53706, (3)Research Leader, Pioneering Research Laboratory, Agricultural Research Service, U.S. Dept. of Agriculture. Phytopathology 64:1364-1367. Accepted for publication 28 May 1974. DOI: 10.1094/Phyto-64-1364.

Isolates of Corynespora cassiicola from Nigeria, southern U.S., and western Mexico were indistinguishable on the basis of conidial size, shape and growth in culture. Optimum temp for radial growth was 28 C. Development of aerial mycelium was sparse under fluorescent light, but was copious in the dark. One group of isolates was highly virulent on tomato and eggplant, and moderately virulent on sesame and cotton. These isolates came from tomato, Calopogonium mucunoides and Synedrella nodiflora in Nigeria, and from cucumber and soybean grown in the southern U.S. Another group of isolates from two common Nigerian weeds, Aspilia africana and a Lepistemon sp., were highly virulent on cotton. Such weed hosts probably serve as sources of primary inoculum on tomato and cotton. One Nigerian isolate from papaya attacked only papaya. A second cucumber isolate was specific to cucumber. Other soybean isolates from southern U.S. and Mexico were highly virulent on soybean, sesame, eggplant, and cotton. Although the species has a very wide host range, host-specific strains appear to be numerous and quite varied in the range of their specificity.