Fusarium species associated with preharvest maize ear rot cause stalk rot disease in Ethiopia

Maize (Zea mays L.) ear rot is an important disease hindering maize production, and Fusarium species have been implicated as a primary cause worldwide. The disease causes substantial yield loss and often results in mycotoxin contamination of grain. In the present study, a preharvest maize ear rot survey was conducted in Ethiopia's ten major maize-growing zones during the 2020 and 2021 cropping seasons. The goal was to identify the main Fusarium spp. associated with preharvest ear rots and determine if they could cause stalk rot of maize in Ethiopia. Based on morphological characteristics, 775 Fusarium spp. were recovered and grouped into four main Fusarium species complexes (FSC). Ninety-two representative FSC isolates belonging to eight Fusarium spp. were identified by molecular phylogenetic analysis using concatenated partial sequences of translation elongation factor-1α (TEF1-α) and RPB2. The analysis of variance showed isolates selected from all eight identified Fusarium spp. caused maize stalk rot disease symptoms with significant differences in disease severity (p<0.001) when tested in a pathogenicity assay. Furthermore, F. falciforme, F. oxysporum f.sp. Ciceris, and F. cf. tjaetaba are reported for the first time as possible causal agents for maize ear rot in Ethiopia. Knowledge of the possible agents (pathogens) associated with maize ear rot and their potential to cause maize stalk rot disease will help develop effective integrated management strategies for these diseases in Ethiopia.