Studies on cultural and morphological variation among 20 isolates of fusarium oxysporum causing wilt of tomato

Twenty isolates of Fusarium oxysporum causing wilt of tomato were recorded for its cultural and morphological variations. The Fusarium oxysporum isolates Fs4 , Fs8 , Fs 11 , Fs12 , Fs14 , Fs15 , Fs16 , Fs17 , Fs19 , Fs20 having the radial colony growth between diameter of 86 mm to 90 mm were among the fast growing category whereas isolates Fs1 , Fs3 , Fs10 , Fs13 , Fs18 showed colony growth between 64 mm to 80 mm classified as medium growing and bellow 64 mm growth of isolates were recorded as slow growing. The biggest size macro-conidia were obtained in isolates Fs 18 ( 31 – 33 × 5 – 6 µm) whereas, the smallest size were obtained from isolate Fs6 ( 12 – 14 × 3 – 4 µm ). The biggest size micro-conidia were obtained in isolate Fs18 ( 8 – 11 × 1 – 3 µm ) whereas, the smallest size were obtained from isolates Fs5 and Fs6 ( 3 – 4 × 1 – 2 µm ). The number of septa in macro and micro-conidia were3-4 and 0-1 respectively all conidia showed hyline nature. The Macro-conidia were sickle shaped with blunt ends and micro-conidia were round to oval. Chlamydospores were recorded from all 11 days culture of F. oxysporum . The highest dry mycelium weight was obtained from the isolate Fs13 having weight 188.0 mg and minimum dry mycelium weight 133.0 mg was obtained from the isolate Fs8.