An investigation into Fusarium spp. associated with coffee and banana plants as potential pathogens of robusta coffee

Abstract

Studies were conducted on fungi isolated from coffee trees affected by Fusarium xylarioides (Heim & Saccas) Steyaert to establish their pathogenicity and identify possible alternate hosts. Coffee and banana plant samples were collected from individual coffee farmers from the coffee growing districts of Mukono, Mpigi, Mubende, Kabarole and Kibaale. The studies were aimed at isolating the type of Fusarium species affecting coffee trees, identifying and characterizing them. Various Fusarium species were found associated with robusta coffee berries, stems and roots. These included Fusarium xylarioides, F. stilboides Wollen-webber & Reiking, F. solani (Mart.) Saccas, F. lateritium Nees, F.semitectum Berk & Rav, F. oxysporum Schlecht, F. moniliforme Sheldon and F. acuminatum Ell. & Ev. Also recovered from banana roots and pseudo-stem were F. xylarioides, F. oxysporum, F. solani, F. acuminatum and F. moniliforme. Fusarium xylarioides, F. oxysporum and F. solani were isolated most frequently from roots followed by stems and rarely on berries. Both F. stilboides and F. lateritium were next in abundance and were isolated mostly from berries. In culture, F. xylarioides isolates showed two types of colonies: one was soft, slimy and smooth, while the other was wrinkled. The two F. xylarioides isolates were not compatible. The five commonly isolated Fusarium species from robusta coffee produced symptoms on inoculated robusta coffee clones but F. xylarioides isolates induced the more severe symptoms, killing the greatest number of shoots.