Biocidal effects of aqueous extracts of Senna alata L. on yam (Dioscorea rotundata Poir) tuber rot in storage

The biocidal efficacies of different concentrations of aqueous leaves extract of Senna alata against yam tuber rot pathogens were determined. Cold and hot aqueous leaves extract were used to poison prepared medium before inoculating with the isolated rot fungi viz; Botryodiplodia theobromae, Aspergillus flavus, Aspergillus niger and Aspergillus glaucus from rotten yam tuber. Thirty grams of S. alata in 100ml of hot water mostly inhibited the radial mycelia growth of all the rot organisms: B. theobromae (94.30%), A. flavus (100.00%), A. glaucus (90.00%) and A. niger (97.50%). Similarly, 50g of S. alata in100ml cold water inhibited the radial mycelia thrive of B. theobromae (99.70%), A. flavus (100.00%), A. glaucus (100.00%) and A. niger (89.20%) while 10, 20 and 30g of S. alata in 100ml hot water inhibited the radial mycelia growth of A. flavus to 93.33, 96.67 and 100.00% respectively. The use of leaf extracts of Senna alata for the control of yam tuber rot is recommended to farmers and yam consumers since they are not toxic when consumed and S. alata is widely distributed within the localities.