Efficient and large-scale field screening procedure for maydis leaf blight

Abstract

Bipolaris maydis (Y. Nisik. & C. Miyake) Shoemaker is a necrotrophic fungal pathogen that causes maydis leaf blight (MLB) also known as Southern corn leaf blight (SCLB) mainly infects maize leaves. Lesions are initially small and diamond-shaped, and then become elongated as they mature. Under severe disease pressure, lesions may coalesce, blighting the entire leaf. This disease is found in almost all maize-growing regions of the world including India and significantly affects maize productivity. In the present study, an efficient and large-scale field screening procedure was developed to identify resistant maize genotypes. The plants were inoculated at the 5–6 leaf stage by placing around 10–20 sorghum grains prior infested with the fungus into the whorl of each maize plant. Primary inoculum is eventually dispersed by environmental factors, causing multiple cycles of infection that assure a high uniform disease pressure over the entire field. The intensity of the disease was recorded as disease scoring on a scale of 1–9 at the pre-flowering, tasseling and silking stage.