Chickpea Fusarium Wilt ( <i>Fusarium oxysporum</i> f.sp. <i>ciceris)</i> : Current status and biophysical factors influencing its epidemics in western Amhara, Ethiopia

Abstract Background: Chickpea, a legume of immense nutritional and economic significance, has carved a unique niche in the small cereal-based cropping system in the highlands of Ethiopia. However, its productivity in Ethiopia is too low compared to its attainable yield and the world average. This could be partially attributed to chickpea Fusarium wilt, one of the most devastating diseases that give rise to considerable grain yield loss. Chickpea field surveillance was conducted to quantify the status of chickpea Fusarium wilt intensity and its association with biophysical and socio-economic factors. Methods: Chickpea Fusarium wilt incidence and severity were assessed across six districts, 18 Kebele (the lowest administrative unit), and 303 farmers’ fields using random sampling design methods during October–January cropping seasons of 2022/2023 and 2023/2024. A logistic regression model was used to associate disease intensity parameters with biophysical factors. Results: The findings depicted that chickpea Fusarium wilt was ubiquitously detected in all inspected chickpea-sown fields. The disease incidence and percent severity index (PSI) were significantly impacted by the biophysical factor studied. The minimum wilt incidence (8.63%) and PSI (8.78%) were noted from chickpea fields planted late in the season after four or more consecutive years of crop rotation practice. Conversely, the maximum wilt incidence (43.74%) and PSI (39.58%) were obtained from fields owning early planted chickpeas after one year of crop rotation practices. Pathogenicity tests revealed that all isolates were found to be pathogenic; inducing yellowing and wilting symptoms with a mean incidence percentage of 7.94–62.96%. Thus, about 61% of the isolates were moderately pathogenic, causing a wilt incidence of 30–50%. The rest of 22.2% and 16.7% of the isolates were highly pathogenic and less pathogenic by inducing above 50% and less than 30% mean wilt incidences, respectively. The regression analysis depicted that the duration of crop rotation retained a strong negative association with the incidence of chickpea Fusarium wilt. Additionally, planting time and weed density showed a moderate association with the disease intensity in a negative manner. Conclusion: Delayed planting, long-term crop rotation practices, and maintaining weed-free environments are pivotal for effective management of chickpea Fusarium wilt. The combined, synergistic implementation of these practices is crucial for reducing disease intensity and restraining chickpea yield loss. Future efforts should also focus on developing chickpea genotypes with improved resistance.