First Report of Stemphylium vesicarium Causing Onion Stemphylium Leaf Blight in Ethiopia

摘要

A suspected fungal disease was observed on onion leaves during survey in onion fields of the central rift valley of Ethiopia in the offseason in 2019. The disease symptoms were round to oval small spots on onion leaves which coalesce to form blighted leaves that change to brown lesion and black sporulation with time. The disease was of high incidence (up to 95.2%) and severity (up to 4.67) where in some fields it has been causing early plant senescence and reduced bulb size during harvest with massive yield loss, named to be "Yeshinkurt Ebola" to mean "Ebola of onion" by farmers. Dirty white to light grey front colony color and light brown to deep brown reverse colony color with alternative white and brown band fungal growth were isolated from infected onion leaf samples. The conidia were olive brown, oval to ovoid, oblong and ovoid to oblong are born on conidiophores. Pathogenicity of the pathogen was confirmed on 45-days-old onion (cv. Nafis) plant, and it was identified as Stemphylium vesicarium based on cultural, morphological and pathogenic results. This is the first report of S. vesicarium, the causative agent of onion stemphylium leaf blight.