Morphological and molecular characterization of Exserohilum turcicum causing turcicum leaf blight in sorghum

Abstract

Sorghum (Sorghum bicolor [L.] Moench), popularly known as jowar, is one of the oldest cultivated cereal crop and serves as a major source of food, fodder and industrial raw material in many semi-arid regions of the world. However, the productivity and profitability of sorghum cultivation are severely constrained by several diseases, among which turcicum leaf blight, caused by Exserohilum turcicum (Pass.) Leonard and Suggs, is one of the most destructive foliar diseases. The research aimed to characterize the causative agent of turcicum leaf blight disease in Northern Karnataka, India, caused by Exserohilum turcicum (Passerini) Leonard and Suggs. Leaf samples were collected from infective fields in major sorghum growing districts of North Karnataka in 2025-26. A total of 30 fungal isolates were examined for cultural, morphological and molecular characteristics and were identified and E. turcicum. The isolates were shown variation in there colony color, i.e., Dull grey to black, and colony texture ranged from coarse to smooth. Mycelial width varіed from 2.94 µm іn Et-10 to 5.10 µm іn Et-1 and Et-17. The conidial shapes were observed to be spіndle and elongated, each wіth a small basal protrudіng hіlum, with conidial septa ranging from 3-7. Similarly, conidial length varied from 58.89 µm to 15.76 µm. ITS gene sequencing analysis made it possible to verify the identities of fungal strains and phylogenetic relationship of selected isolates. The ITS gene sequencing of isolates showed high similarity of (100 %) with reference isolates of GeneBank. The findings of this study will serve as a baseline for future studies and will help to minimize yield losses.