Phytotoxic Potentials of Cold and Hot Aqueous Extracts of Chromolaena odorata against Fungal Deteriorating Agents of Yam Tubers (Dioscorea rotundata, Poir) after Harvest

Abstract

The antifungal activities of cold and hot aqueous extract of C. odarata against four isolated fungi namely Aspergillus flavus, Aspergillus glaucus, Aspergillus niger and Botryodiplodia theobromae causing post-harvest rot disease of yam tubers were investigated. All the concentrations; 10g/100ml to 50g/100ml of both hot and cold extract of C. odorata inhibited significantly the radial mycelial growth of all the test fungal organisms with percentage inhibition ranging from 77.78% to 98.89%. However, 10/100ml of cold extract and 30g/100ml of hot extract inhibited B. theobromae to 90.48% and 97.14% respectively; 20g/100ml of cold water extract and 30g/100ml of hot extract inhibited B. theobromae to 90.48% and 97.14% respectively; 20g/100ml of cold extract and 30g/100ml of hot extract inhibited A. flavus to 95.56% and 98.22% respectively; 30g/100ml of cold and hot extract inhibited A. glaucus to 97.77% and 98.89% respectively and 70g/100ml of cold extract and 10g/100ml of hot extract inhibited A. niger to 91.92% and 98.08% respectively. Both hot and cold extract of C. odorata were found to be very potent against all the isolated yam tuber rot pathogens. The test plant therefore could serve as preferred alternatives to synthetic chemicals because it is readily available and produced no known negative effect on the environment.