Molecular Characterization of Pathogenic Fungi Causing Post-Harvest Rot in Stored Yam in Ebonyi State

Post-harvest yam rot caused by pathogenic fungi represents one of the most economically devastating challenges in Nigeria's yam production system, with estimated losses of 20 to 40 percent annually. In Ebonyi State, a major yam-producing state in the South East, storage losses are frequently attributed to fungal decay, yet the causal organisms have not been systematically characterized using molecular methods. This study identifies and molecularly characterizes the fungal pathogens responsible for post-harvest rot in stored yam (Dioscorea rotundata) in Ebonyi State using morphological observation, culture-based isolation, and ITS region sequencing. Yam samples exhibiting decay symptoms were collected from 15 farm storage facilities and four major markets in Ebonyi State. Isolated fungi were cultured, morphologically described, and subjected to DNA extraction and PCR amplification using universal ITS primers. Phylogenetic analysis was performed using MEGA 11 software. Seven fungal species were identified, with Fusarium oxysporum, Aspergillus flavus, and Botryodiplodia theobromae confirmed as the dominant pathogens by both morphological and molecular criteria. Environmental conditions, including storage humidity and ventilation, were identified as key drivers of pathogen incidence. The study recommends improved yam barn ventilation and fungicide treatment of seed yams as immediate management interventions in Ebonyi State. Keywords: yam rot, pathogenic fungi, molecular characterization, Dioscorea rotundata, Ebonyi State