Characterization of Alternaria species causing taro (Colocasia esculenta (L.) Schott) leaf blight and evaluation of their susceptibility to fungicides and Trichoderma biocontrol agents

Abstract

The output of taro in Ethiopia’s main growing regions has recently suffered significantly from Alternaria species infection, both in terms of quantity and quality. In the present study, Alternaria species that cause taro leaf blight were isolated, characterized, and their susceptibility to Trichoderma biocontrol agents and chemical fungicides were assessed under in vitro condition. Using food poisoning procedures and the dual culture method, the isolates’ susceptibility to fungicides and biocontrol agents was examined. The conidial length and breadth of the Alternaria isolates were 26.10–42.50 μm and 10.20–18.50 μm, respectively. The maximum mycelial growth of the isolates was supported by the host leaf extract medium. The pathogenic isolates grew best in optimum growth conditions with an incubation temperature of 25°C and a pH level of 6.5. Even at low doses, sancozeb was more effective than curzate against Alternaria isolates. Additionally, compared to T. harzianum, the biocontrol agent T. viride showed a greater mycelial growth inhibition of the test pathogen. This suggests that Alternaria isolates that cause taro leaf blight are susceptible to biocontrol agents. Therefore, it was advised that Trichoderma species be tested for effectiveness against the test pathogens in both greenhouse and field conditions.