Pathogenicity of Cylindrocladium clavatum Causing Potato Tuber Rot. H. A. Bolkan, Associate Professor, Departamento de Biologia Vegetal, Universidade de Brasilia, Brasilia DF, 70.910 Brazil. Wilma R. C. Ribeiro, Graduate Research Associate, and O. C. DeAlmeida, Graduate Student, Departamento de Biologia Vegetal, Universidade de Brasilia, Brasilia DF, 70.910 Brazil. Plant Dis. 65:47-49. Copyright 1981 American Phytopathological Society. DOI: 10.1094/PD-65-47.

Peanut, eucalyptus, soybean, pepper, tomato, tobacco, papaya, and eggplant were tested for response to artificial inoculation with Cylindrocladium clavatum isolated from a potato tuber. Tobacco, tomato, papaya, and eggplant were not affected by C. clavatum, but severe root rot developed on peanut, and eucalyptus, soybean, and pepper showed slight to moderate symptoms of root infection. An in vitro soil temperature of 25 C and moisture level of –3 bars were more favorable for tuber surface rot development than lower soil temperatures or a soil moisture level of –86 bars. Tuber rot was less at 15 and 20 C, and at 10 C no measurable disease resulted. The optimum temperature for vegetative growth and conidial germination of C. clavatum correlates well with the effect of soil temperature on disease development on potato tubers.