EFFICACY OF DIFFERENT MICROBIAL ANTAGONISTS IN CONTROLING FUSARIUM WILT OF TOMATO

Abstract

The experiment was conducted in the Disease Diagnostic Laboratory and Net house of Department of Plant Pathology, Sher-e-Bangla Agricultural University, Dhaka during the period of July 2011-June 2012 to search suitable antagonistic microorganism against Fusarium oxysporum f. sp. lycopersici causing Fusarium wilt of tomato.Twenty probable antagonistic bacterial isolates were isolated from rhizosphere soil and screening was done against F. oxysporum f. sp. lycopersici to detect the promising antagonistic microorganism. One antagonistic fungal isolate Trichoderma harzianum also collected from laboratory of Bangladesh Agricultural Research Institute (BARI), Gazipur and assayed as antagonist against F. oxysporum f. sp. lycopersici. Out of twenty bacterial isolates, only four isolates (Iso-1, Iso-2, Iso-3 and Iso-4) were found effective in dual culture method. Out of all test organisms, Trichoderma harzianum produced the highest percent inhibition zone (75.75 %) and the lowest percent inhibition zone (28.39 %) was produced by Iso-2. In blotter method, the highest prevalence of Fusarium oxysporum was observed in control (11.25%) while the lowest was in Iso-1 (0.58%). In pot culture, the efficacy of microbial antagonist in controlling Fusarium wilt of tomato was done by root dipping and soil drenching method. The highest disease incidence was observed in control (40% in 20 DAT and 60% in 30 DAT) and the lowest was observed in Iso-1 and T. harzianum (0% in 20 DAT, 10% in 60 DAT). Disease severity was also the lowest (PDI 0.00% in both 10 DAT and 20 DAT and 3.33% in 60 DAT) in Iso-1. Thus Iso-1 can be used as a bio-control agent against F. oxysporum f. sp. lycopersici causing wilt of tomato.