Performance variation in growth and sporulation of isolates of Alternaria alternata Fr. Keissler causing blight disease in Mulberry

Abstract

Mulberry Alternaria blight (Alternaria alternata) is one of the foliar devastating diseases and reduces leaf quality and yield. Studying the cultural characters of the pathogen is the first and most important basic step in identification process. The results of cultural studies revealed that PDA was the best medium for supporting the good radial growth of the isolate Aa-1, Aa-2, Aa-4 and Aa-7 with the maximum radial growth of 90.00 mm after ten days of inoculation. Whereas, isolate Aa-2 and Aa-6 yielded maximum growth of 90 mm in Sabouraud's dextrose agar medium and isolate Aa-8 and Aa-9 in oat meal agar medium. Maximum growth (90 mm) in corn meal agar (Aa-7) and in Richards synthetic agar medium isolate Aa-4, Aa-6 and Aa-10 recorded good growth. Dry weight of mycelium of the different isolates A. alternata studies revealed that isolate Aa-3 showed maximum dry mycelial weight of the fungus noticed in Host leaf extract broth (998.71 mg) which was followed by Isolate Aa-2 (997.93 mg) and Isolate Aa-5 (997.4mg) in Sabouraud's dextrose broth. Very good sporulation of the Isolate Aa-1 on Potato dextrose broth, Host leaf extracts broth, Oat meal agar broth and Corn meal broth was recorded. The Potato broth also supported good sporulation of three isolates viz: Aa-1, Aa-5 and Aa-9 whereas, by Host leaf extract broth and corn meal broth supported good sporulation of Isolate Aa-4 and Aa-5 respectively.