Survey of Erwinia Soft Rot on Irish Potato (Solanum tuberosum) in Kogi State, North Central Nigeria

Irish potato (Solanum tuberosum) is increasingly cultivated in upland areas of Kogi State, where favourable temperatures during the dry season permit off-season production. Erwinia soft rot, caused by Pectobacterium carotovorum subsp. carotovorum, is a post-harvest bacterial disease associated with rapid tissue maceration and significant tuber losses. This study evaluated the incidence and distribution of Erwinia soft rot in potato tubers from field plots and market storage points across three local government areas in Kogi State. Sixty tuber samples were collected at harvest and re-evaluated following 14 days of ambient storage. Bacterial isolation on crystal violet pectate medium and biochemical testing confirmed P. carotovorum subsp. carotovorum as the predominant causal agent. Post-harvest soft rot incidence rose from 11 percent at harvest to 46 percent after two weeks of uncontrolled ambient storage. High ambient temperatures (averaging 31 degrees Celsius) and physical injury during harvesting were the primary predisposing factors identified. Field incidence of blackleg symptoms, a related manifestation of Erwinia infection, was 18 percent, suggesting seed-borne inoculum as a primary infection source. Growers in the survey were largely unaware of soft rot as a distinct entity and typically attributed storage decay to heat. The study recommends the promotion of cool dry storage infrastructure, tuber curing before storage, and evaluation of copper-based bactericides for field blackleg management. Keywords: potato, Erwinia soft rot, Pectobacterium, post-harvest, Kogi State.