Pathogenic Variability of Isolates of Exserohilum turcicum, Incitant of Leaf Blight of Maize

Variability studies on pathogenicity were conducted using seven isolates of Exserohilum turcicum (Pass.) from maize and one isolate from sorghum by spray inoculation technique on both maize and sorghum cultivars. Among the tested isolates, the isolate Et4 (Warangal) recorded the maximum Per cent disease index (PDI) (36.0), virulence index (9.2), lesion length (13.4 cm) and shortest latent period (4.00 days) on maize, while the minimum PDI (13.3), virulence index (1.7) and longest latent period (8.0 days) was noticed by the sorghum isolate and isolate Et5 from Khammam district produced minimum (4.23 cm) lesion length. Whereas on sorghum the maximum PDI, virulence index, lesion length and shortest latent period were observed in the isolate Et6 from Mahaboobnagar district followed by the sorghum isolate while the minimum PDI, virulence index, lesion length and longest latent period was recorded by the isolate Et3 from Guntur district followed by the isolate Et5 from Khammam district. The remaining isolates i.e., Et1, Et2 and Et7 recorded similar type of reaction on both maize and sorghum.