Fusarium boothii, Fusarium meridionale, and Fusarium temperatum Are Emerging Preharvest Maize Ear Rot Pathogens in Ethiopia.

Abstract

Fusarium ear rot (FER) and Gibberella ear rot (GER) caused by Fusarium species are major diseases affecting maize production in Ethiopia. In addition to reducing quality and yield, these fungi can produce mycotoxins that contaminate maize kernels and, thereby, pose health hazards to humans and livestock. A survey was conducted in 10 administrative zones of Ethiopia within the major maize-growing regions of the country to identify the species of Fusarium associated with ear rot. Twenty kernels were sampled from ears randomly collected from each zone (12 ears per field, 24 fields per zone). Ninety-two fungal isolates recovered from the kernels were tentatively identified as Fusarium based on morphological traits. Subsequently, the species identity of each isolate was determined by DNA sequence analysis of a portion of the translation elongation factor 1-α gene and two noncontiguous fragments of the RNA polymerase II subunit gene. Based on phylogenetic analysis of the data, 37.3% of the isolates recovered from maize kernels were from three species that have not been reported previously in Ethiopia: Fusarium boothii (4.3%), F. meridionale (10.2%), and F. temperatum (22.8%). Completion of Koch's postulates with selected isolates confirmed that these three species can cause maize ear rot. Information on causal agents of maize ear rots in Ethiopia should be taken into consideration when developing disease management strategies, including breeding for resistance.