Epidemiology, characterization, and biocontrol of coffee berry disease in the Gedeo zone, southern Ethiopia

Abstract Coffee berry disease is the most damaging fungal disease of coffee in the Gedeo zone, which results in substantial yield losses. The status of the coffee berry disease is unknown, and there is limited information on characterization and in vitro bioassay against Colletotrichum isolates in the Gedeo zone. Therefore, this study was carried out to assess the prevalence and influence of biophysical factors on coffee berry disease, to characterize the Colletotrichum sp. cf. kahawae , and to examine the antagonistic potential of different biocontrol agents against Colletotrichum sp. cf. kahawae . Coffee berry disease incidence and severity were assessed in 115 fields in five districts, and the isolates were characterized morphologically. The effect of biophysical and management factors on disease intensity was computed with logistic regression. The efficacy of selected bioagents was evaluated under in vitro conditions arranged in completely randomized design with three replications. Mycelia inhibition percentage data was subjected to ANOVA, and means were separated by HSD test at p < 0.05. Coffee berry disease was prevalent in all fields, exhibiting substantial spatial variability; disease incidence and percentage severity indices ranged from 27 ± 6% to 91 ± 2% and 24 ± 3% to 79 ± 8%, respectively. Logistic regression confirmed that biophysical and management factors significantly modulated disease intensity. Moreover, the morpho-cultural characterization revealed phenotypic variation among the recovered Colletotrichum sp. cf. kahawae isolates. Aspergillus terreus exhibited high in vitro mycelial growth inhibition against isolates KH-02 and KG-04 in dual culture assays, achieving 79.7% mycelia inhibition, while Trichoderma spp. isolate CPS-ef0026, and T. virens also demonstrated a potential bioagent. However, to disclose the diversity of the pathogen in the study areas, it is also important to examine the aggressiveness of Colletotrichum sp. cf. kahawae isolates in more detail utilizing a wide range of advanced techniques, and testing the effectiveness of biocontrol agents across various isolates is required to validate this.