Abstract

                                Basal rot disease infected onion bulbs were collected from fifteen places of Tamil Nadu, India. Among the fifteen isolates screened for virulence, DNSFOC1 isolate collected from Sempatti in Dindugal district recorded maximum (88.45) per cent disease infection under artificial inoculation. DNSFOC1 significantly recorded 29.93 mm mycelial growth per day. The length of macroconidia varied from 20.25 to 27.43 μm and the width ranged from 2.36 to 3.16 μm. The length of microconidia varied among the isolates from 7.10 to 8.43 μm and the width ranged from 2.14 to 2.67 μm. Compact, fluffy and sparse colony types were observed among the isolates. Significant variation was observed in morphological character and virulence among the Fusarium oxysporum f. sp. cepae isolates.

Key words : onion, morphological character, pathogenicity, Fusarium oxysporum f. sp. Cepae