ABSTRACT

Three varieties of gamma (y) irradiated and non-gamma irradiated cassava (SMS 909-25, COL 2215 and COL 1734) were investigated for susceptibility to post-harvest fungal rot by Botryodiploidia theobromae, Penicillium oxalicu,n, Aspergillus niger, Fusarium solani and Macrophoniina phaseolina. These moulds were inoculated into the tuber samples at wound depths of 10mm with either single or paired cultures and stored at room temperature (26 ± 2°C) and polyethylene bags (18j.tm thickness). In COL 2215 at room temperature, the most extensive rot developed with M phaseolina (13.50 ± 0.10mm) for single cultures while pair- cultures of P. oxalicum and M phaseolina produced 19.50 ± 0.05mm for irradiated cassava; U-M phaseolina produced 15.50±0.71mm while P. oxalicum and M phaseolina produced 2 1.50± 0.71 in non-irradiated cassava. The minimum rot development occurred in COL 1734 for single culture involving P. oxalicurn (6.50 ± 0.05mm) while pair-cultures 'of B. theobromae and A. niger produced 13.00 ± 0.00mm for irradiated cassava. P. oxalicum produced 8.50±0.71mm for single while P. oxalicum + F. solani produced 13.75±0.72mm for non-irradiated cassava. Generally, significant (P>0.05) rot was recorded for non-irradiated than irradiated cassava varieties analyzed. In polyethylene bags, COL 2215 showed the highest zone of rot (16.50 ± 0.05mm) with M. phaseolina for single cultures while pair- cultures of P. oxalicum and M phaseolina produced 21.63 ± 0.03mm compared to 13.50±0.10mm with M phaseolina and 19.50±0.06mm with P. oxalicuin and M phaseolina at room temperature, whereas COL 1734 showed the minimum zone of rot with M. phaseolina (13.50± 0.00mm) and P. oxalicurn and M phaseolina (17.50±0.21mm) compared to the zone of rot with M phaseolina (9.00±0.15) and P. oxalicuni and M phaseolina (14.50±0.20mm) at room temperature. M phaseolina showed the highest zone of rot development in gamma and non gamma irradiated tuber irrespective of the storage condition. Irradiated cassava tubers showed more resistant to deterioration in storage than non-irradiated tubers.