Morphological Evaluation of Bacterial and Fungal Pathogens Associated with Plantain (Musa paradisiaca L.) Rhizosphere

Abstract

Plantain (Musa paradisiaca), a staple crop in many tropical regions, is a vital source of food and income for millions of smallholder farmers, contributing significantly to global agricultural economies. This study investigated the root rot diseases affecting plantain, with root samples collected from the Rivers State Institute of Agriculture Research and Teaching Farm (RIART). Visual assessment was employed to evaluate and quantify lesions and damage on the plant roots. Thereafter, standard cultural techniques were employed for the isolation and characterization of associated pathogens. The results revealed two distinct disease symptoms: dry root rot, characterized by dehydrated and necrotic tissues, and soft rot, marked by watery and macerated tissues. Fusarium oxysporum was identified as the primary cause of dry root rot, consistent with its role in vascular wilt and tissue desiccation, while Pseudomonas sp. was confirmed as the main agent of soft rot, associated with pectolytic enzyme activity. Five fungal isolates (F. oxysporum, Candida sp., Aspergillus flavus, A. niger, and Mucor sp.) were identified, with F. oxysporum and Pseudomonas sp. demonstrating strong pathogenicity in tests, while control plants showed no symptoms. The high incidence of Aspergillus spp. and Candida sp. suggested their roles as opportunistic or secondary colonizers, whereas Mucor sp. was associated with highly deteriorated tissues. The study concluded that both fungal and bacterial pathogens significantly contributed to plantain root rot, with F. oxysporum and Pseudomonas sp. driving the predominant disease symptoms. It is recommended that integrated disease management strategies, including resistant plantain varieties and targeted biocontrol measures, be developed to mitigate the impact of these pathogens on plantain production.