Studies on cultural characteristics of Fusarium isolates causing panama wilt of banana under West Bengal

Banana wilt caused by Fusarium oxysporum f.sp. cubense is a serious disease of the crop & causes economic crop loss in every year particularly in some susceptible commercial cultivars. 14 isolates of the pathogen were collected from different banana cultivars in West Bengal. During invitro culture PDA was recorded to be the best medium for all the isolates. Great variation was recorded not only in the relative growth but also rate of growth and pigmentation in the culture medium. Maximum radial growth (90 mm) was measured in FOC-3 & FOC-10 in PDA medium & FOC-4 in CDA medium after 9 days of inoculation. The slowest grower (75mm) isolates identified as FOC-5 in PDA medium & FOC-1 (35mm), FOC-6 (37mm) & FOC-7 (26.9mm) in CDA medium & variation among the isolates tested are statistically significant. Isolates were showed specificity with their nutritional requirement. All the tested pathogen prefers asparagin as a source of protein during artificial culture. Spore population of all the isolates was counted and FOC-3 showed highest population irrespective of macro-micro conidia. Macro-spore size varies from 14.38x3.13µ to 28.57x3.39µ and microspore size varies from 5.65x2.05µ to 9.49x2.60µ. All the fourteen isolates were cultured & measured their relative growth using Czapexdox Agar medium. Different nitrogen sources (KNO3, NH4Cl, Asparagin, and NaNO3) were used in the medium to know the most suitable compound for their utilization during artificial culture.