Author(s):

K Rajamohan, R Udhayakumar, S Sanjaygandhi, L Vengadesh Kumar, M Thamarai Selvi, S Sudhasha and R Yuvarani

Abstract: The study was undertaken to investigate the biocontrol potential of the native antagonists for the efficient usage of <em>Pseudomonas fluorescens, Trichoderma viride </em>and<em> Glomus mosseae </em>for the successful biological management of <em>F. oxysporum </em>f.sp. <em>cepae</em> causing basal rot of onion. In general all the native <em>Trichoderma</em> spp. tested significantly inhibited the mycelial growth of <em>Fusarium oxysporum </em>f.sp.<em> cepae</em>. However, among the isolates, the isolate Tv_5` showed the maximum inhibition and significantly inhibited the growth of <em>F. oxysporum </em>f.sp.<em> cepae</em> (15.42 mm), which was 82.86 per cent reduction on the growth of the pathogen when compared to control. Among the <em>Pseudomonas </em>isolates, Pf₂ produced significantly the minimum mycelial growth (23.32 mm) accounting for 80.82 per cent reduction on the mycelial growth of <em>F. oxysporum </em>f.sp.<em> cepae </em>over control. The results obtained on the efficacy of combined application of antagonists and <em>G. mosseae</em>, soil application with combination of <em>T. viride </em>(Tv₅) and <em>P. fluorescens </em>(Pf₂) plus soil application of <em>G. mosseae</em> treatment (T₇) recorded the minimum wilt incidence (4.82 %). Similarly, the same treatment recorded the maximum growth parameters such as shoot length (35.42 cm), root length (5.0 cm) and bulbs (6.0). The control recorded the minimum growth parameters such as shoot length (18.62 cm), root length (2.5 cm) and number of bulbs per plant (1.0).

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