Evaluation of cassava clones for resistance to anthracnose disease using phytotoxic metabolites of Colletotrichum gloeosporioides/. sp. manihotis and its correlation with field disease reactions

Abstract

Colletotrichum gloeosporioides f sp. manihotis, the causal agent of cassava (Manihot spp) anthracnose disease produces toxic metabolites in culture. Symptoms induced on cassava leaves and stem cuttings by the toxic metabolites are similar to those induced by the pathogen. Twenty one M. esculenta clones were screened under field conditions using natural infection and with the phytotoxic metabolites of the pathogen. Results indicated that 8 cassava clones were resistant while the other 13 clones were susceptible at varying degrees. Results from in vitro screening of cassava using phytotoxic metabolites compared favorably with field screening based on natural infection. Use of toxic metabolites appears to be a more effective assay for screening cassava clones for resistance to anthracnose disease than those based on natural disease infection.