Morphological variability of Fusarium oxysporum f. sp. capsici (FOC) isolates infecting pepper (capsicum annum L.) landraces in West Gojjam Zone, Ethiopia

Pepper is an important source of income for Ethiopian smallholder farmers. However, Fusarium wilt has been hindering pepper production and productivity. This study characterized the morphological variability of Fusarium oxysporum f. sp. capsici isolates collected from potential pepper production areas of West Gojjam, Ethiopia. A total of 196 symptomatic plant samples were collected and screened. Based on the macroscopic and microscopic characteristics, 67 F. oxysporum f. sp. capsici isolates were characterized. The distribution of F. oxysporum varied among districts, of which the largest number of the Fusarium isolates was recorded in Womberma (36%) and the lowest was in Burie Zuria (15%). The frequency of F. oxysporum occurrence varied in different plant parts including, roots (56.2%), stem (31.7%), and leaf (12.1%). Colony color varied from white (43.28%) to pink (10.45%). The radial growth of the colony varied from 2.5 - 4.5 cm on the 7th day of culture, of which, 6 isolates had >3 cm, 37 isolates had 3-4 cm, and 24 isolates had >4 cm radial growth. Two types of shapes were recorded with almost similar proportions (50.75% filamentous and 49.25% round). From the total 67 identified isolates, 74.6% had adherent mycelial and 26.4% of them had fluffy growth pattern. Microscopically, all the isolates produced micro- and macro-conidia. The microconidia had oval (67.16%), kidney (29.85%), and globose (2.99%) shaped morphology. The macroconidia were with curved (25) and straight (42) shaped morphology, with three to five septa. The isolates had an entire (73%) and filiform margin (27%). Further, pathogenicity and molecular characterization needs to be conducted.