The mycological assessments of postharvest rot of irish potato from selected market within Kaduna metropolis, Nigeria were carried out. Fifteen (15) tubers of irish potato showing symptom of rot were collected from (4) four different market, totaling sixty (60) samples all together. The selected markets were; Ungwan rimi, Malali, Chechenia and Kaduna State University (KASU) school markets. Segment of the tissue from the margins of the spoilt irish potato were cut with sterile scalpel and were placed on the prepared sabouraud dextrose agar plate (SDA) in petri-dishes and were incubated at 28±2ºC for 5days. The mycelia of fungi isolates were viewed under the microscope using 4X and 40X magnifications. Pathogenicity test were carried out on heathy tubers. The fungi identification were made using identification atlas. Fungi such as Rhizopus stolonifer, Fusarium oxysporum, Aspergillus niger, Aspergillus flavus, Penicillium sp and Mucor racemosus were isolated with different frequencies from the sampled potato. Irish potato from Ungwan rimi market had R.stolonifer 6(40.0%) F.oxysporum 4(26.7%) A.niger 2(13.3%) A.flavus 1(6.7%) Penicillium species 2(13.3%). Irish potato from Malali market had R. stolonifer 4(26.7%) F.oxysporum 3(20.0%) .A.niger 2(13.3%) A.flavus 3(20.0%) Penicillium sp 2(13.3% ) M.racemosus 2(13.3%), Irish potato from Chechenia market had R.stolonifer 6(40.0%) F.oxysporum 4(26.7%) A.niger 2(13.3%) Penicillium sp 2(13.3%) M.racemosus 1(6.7%). Irish potato from Kasu market had R.stolonifer 5(33.3%) F.oxysporum 3(20.0%) A.niger 3(20.0%) A.flavus 2(13.3%) Penicillium sp 1(6.7%) M.racemosus 1(6.7%) respectively. The results from the pathogenicity test showed that fungi induced different level of decay with R.stolonifer as the most virulent fungus followed by F .oxysporum and M.racemosus as the least virulent fungus. This study showed that many fungus have been found to cause storage rot of irish potato within selected markets of the metropolis. This pathogen leads to the enormous loss of potato tubers. In order to prevent the fungi causing rot in irish potato preventive measures such as adequate storage facilities and segregation of rotten irish potato tubers from healthy ones should be duly exercised.
