Vol. 12, Issue 4 (2023)

Author(s):
Arghya Banerjee and Partha Sarathi Nath

Abstract:
Among the foliar diseases of maize, the turcicum leaf blight (TLB) also called as Northern corn leaf blight caused by Exserohilum turcicum (Pass) Leonard and Suggs. (syn. Helminthosporium turcicum Pass.) is having worldwide importance. Turcicum leaf blight is one of the most important foliar fungal diseases affecting photosynthesis with severe reduction in grain yield of more than 50 per cent. The eight (8) Exserohilum isolates (Et1 – Et8) collected from different districts of West Bengal viz., Nadia, Bardhaman, Bankura, Birbhum, Murshidabad, Purulia, Purba Medinipur and Coochbehar districts during Kharif 2017-18 to assess the disease severity and to study variability of the pathogen. The eight single spore-cultures of E. turcicum isolates (Et) exhibited cultural variability in respect of colony colour, colony growth, sporulation and pigmentation on best suited four media such as PDA, MLEA, PCA and PDA+Yeast at different temperature ranges. Colony colour varied from grey to black in colour depending upon the isolates and growth medium. The isolate Et4 (Birbhum), Et6 (Purulia), Et7 (Purba Medinipur) and Et8 (sorghum, Coochbehar) were under the group of profuse to moderate growth was exhibited in the isolates Et1 (Nadia) and Et2 (Bardhaman) while poor restricted growth was observed in the Et3 (Bankura) and Et5 (Murshidabad) isolates. The isolates Et1 (Nadia), Et4 (Birbhum), Et6 (Purulia), Et7 (Purba Medinipur) produced excellent sporulation while the isolates Et2 (Bardhaman), Et3 (Bankura) exhibited good sporulation and showed the similarity with sorghum isolate Et8. The isolates Et1 recorded the maximum (117.26 μm) conidial length and minimum (82.50 μm) conidial length was recorded by the isolate Et5. The isolates that were identical for virulence were dissimilar with RAPD markers. The most virulent Birbhum and Purulia isolates were grouped in different sub groups.