Survey, surveillance and cultural characteristics of Alternaria leaf blight of cotton.

The roving survey undertaken in four districts viz., Parbhani, Nanded, Osmanabad, and Beed of Marathwada region revealed that average Alternaria blight incidence was ranged from 14.60 to 30.03 per cent. Bt. Cotton crop grow in the district of Nanded was found to be affected more with Alternaria blight (overall incidence 30.03%), followed by the district of Parbhani (25.20%), Beed (21.06%) and Osmanabad (14.60%). In Nanded district, maximum disease incidence (32.60%) was recorded in Degloor tahsil and this was followed by Naigaon tahsil (30.00%) and Nanded tahsil (27.50%). Results revealed that all the 11 culture media tested encouraged better growth of A. macrospora. However, potato dextrose agar gave significantly highest radial mycelial growth of 88.18 mm. The second and third best culture media found were Czapek’s dox agar (81.28 mm) and Richards agar (79.75 mm). Ashby’s manitol agar was found least suitable for the growth of test pathogen (39.92 mm). © 2013 Sjournals. All rights reserved.