Survey on the distribution and epidemiology of faba bean gall (Physoderma viciae) in South Wollo, North-Eastern Ethiopia: an emerging threat to faba bean production

Abstract

Faba bean gall, a disease caused by Physoderma viciae, has emerged as a major constraint to faba bean production in the highland areas of northeastern Ethiopia. This study assessed the prevalence, incidence, and severity of faba bean gall across major faba bean-growing districts during the 2022 and 2023 cropping seasons. A total of 200 fields were surveyed, and disease parameters were recorded alongside agro-ecological and management-related variables. The results revealed that faba bean gall was widespread across all surveyed districts, with higher prevalence and severity recorded in 2022, coinciding with increased rainfall, humidity, and prolonged cloud cover. Disease incidence and severity were positively correlated with altitude, particularly in fields located above 2844 m a.s.l., and peaked during the flowering stage. Disease intensity was primarily driven by district, year, altitude, variety, and drainage, with agronomic practices exerting secondary modifying effects. Although Wolkie varieties showed slightly lower disease levels than local landraces, no varieties displayed complete resistance. Logistic regression analysis identified district, year, altitude, variety, and field drainage as the most important independent predictors of faba bean gall incidence and severity, with agronomic practices exerting secondary modifying effects. The findings highlight the urgent need for integrated disease management strategies, emphasizing host resistance, improved drainage, crop rotation, and context-specific agronomic practices to mitigate the impact of faba bean gall in Ethiopia’s highlands.