Onyeka T.J; A.G.O. Dixon, T. Ikotun and K. Wydra
The pathogenicity of microorganisms associated with cassava root rot was determined by an in-vitro method in which cassava storage root slices were inoculated. The various microorganisms isolated from infected cassava were classified according to their ability to cause root rot disease. Four of the nine pathogens frequently associated with cassava root rot samples were able to initiate rot in the pathogenicity test using root slices assay. Three of the pathogen isolates (Botryodiplodia theobromae, Sphaerostilbe repens, Fusarium solani) were used to assess the reactions of six elite cassava genotypes and one African landrace to root rot. The genotypes showed differential response to the three pathogens. Fusarium sp did not cause any appreciable rot in the various cassava genotypes. However, with B. theobromae and S. repens, significant reaction to rot was observed among the different genotypes. 30572 and 92/0057 were the most resistant while TME-1 and 30001 were the most susceptible to root rot.