Identification and pathogenicity of Fusarium species associated with preharvest maize ear rot in Ethiopia

Authors: DERESSA, TEMESGEN - Jimma University; ADUGNA, GIRMA - Jimma University; SURESH, MAHABALESWARA - International Maize & Wheat Improvement Center (CIMMYT); BEKEKO, ZELALEM - Ethiopia Haramaya University; Iriarte Broders, Gloria; Vaughan, Martha; Proctor, Robert; Mehl, Hillary; PRASANNA, BODDUPALLI - International Maize & Wheat Improvement Center (CIMMYT); Opoku, Joseph

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: Corn is an important staple crop, and production has risen over the past few decades in Ethiopia. However, the prevalence of corn ear rot disease and the recent emergence of stalk rot diseases have been significant challenges for growers, reducing productivity in several areas. In a collaborative effort, scientists from Ethiopia and the USDA ARS in Peoria, IL, conducted maize pre-harvest field and laboratory experiments. The aim was to identify mycotoxigenic Fusarium species associated with corn ear rots and investigate if these pathogens could cause the stalk rot disease symptoms observed during field inspections. The research revealed that several mycotoxin-producing fungi were associated with the corn harvested from several regions, and these pathogens could cause stalk rot under controlled conditions. These findings have important implications for agricultural practices in Ethiopia, providing valuable information needed to manage these diseases effectively and sustainably.

Technical Abstract: 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 losses 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. This was to identify the main Fusarium species associated with Fusarium ear rots and determine if they can potentially cause Fusarium stalk rot of maize in Ethiopia. Based on morphological characteristics and molecular phylogenetic analysis using concatenated partial sequences of translation elongation factor-1a (TEF1-a) and RPB2. Ninety-two isolates belonging to eight Fusarium species were identified. These identified isolates belonged to five Fusarium species complex groups with the most predominant group being F. fujikuroi species complex (FFSC) Africa clade and America clade, accounting for 73.9% of the total number of isolates. Representative isolates of all eight Fusarium species 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 causal agents of maize ear rot and their potential to also cause stalk rot will help develop effective integrated management strategies for these diseases in Ethiopia.