Assessment of maize (Zea mays L.) turcicum leaf blight, morphological characterisation of Exserohilum turcicum and response of maize varieties to the disease in Wolaita Zone, Southern Ethiopia

Turcicum leaf blight (TLB), caused by Exserohilum turcicum, is a major foliar disease limiting maize yields in Ethiopia, particularly in humid, moderate-temperature areas. This study aimed to assess the status of TLB, characterise pathogen diversity and evaluate varietal resistance in the Wolaita Zone, Southern Ethiopia. Comprehensive surveys in 4 districts revealed TLB to be widely prevalent, with Damot Sore and Humbo showing the highest incidence (over 90 %) and severity (nearly 73.9 %), underscoring environmental influence on disease distribution. Morphological evaluation of E. turcicum isolates demonstrated marked diversity in colony morphology and growth rates, indicating significant pathogen variability across locations. Field trials with 12 maize varieties under natural TLB infection indicated highly significant differences in disease response and yield. AMH-854 and AMH-851 were the most resistant, exhibiting the lowest final severity indices (19.1–30.6 %) and highest grain yields (up to 94.9 q ha-1), while MH-140 and BH-546 were most susceptible. Disease progression fitted the Gompertz model, highlighting variation in epidemic development among varieties. Correlation analysis showed a negative relationship between disease parameters and yield attributes. The results highlight the urgent need for integrated management, prioritising resistant hybrids and ongoing surveillance to improve maize productivity and sustain disease control in TLB-prone areas.