Int.J.Curr.Microbiol.App.Sci (2020) 9(9): 3491-3495 3491 Original Research Article https://doi.org/10.20546/ijcmas.2020.909.433 Evaluation of Bio-agents against Different Isolates of Macrophomina phaseolina (Tassi) Goid Causing Root Rot in Castor P. V. Vekariya 1* , A. G. Desai 2 and G. P. Gangwar 2 1 Main Oilseed Research Station, Junagadh Agricultural University, Junagadh-362001, Gujarat, India 2 Castor - Mustard Research Station, Sardarkrushinagar Dantiwada Agricultural University, Sardarkrushinagar - 385506, Gujarat, India *Corresponding author ABSTRACT Introduction The fungus Macrophomina phaseolina (Tassi) Goid. a soil inhabiting an important root pathogen in many crops. The disease appears at different growth stage of castor crop and hence, it is named as spike blight, stem blight, twig blight, collar rot and root rot (Moses and Reddy, 1987). Biological control is a potential non-chemical means for plant disease control by reducing the harmful effects of a pathogen through the use of other living entities. Since the M. phaseolina is a soil borne fungus and possess greater problem in managing the disease. Soil borne diseases are difficult to control. Seed treatment with fungicides does not protect the crop for long periods. Soil drenching with fungicides are not economical and they may establish imbalances in the microbial community International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 9 Number 9 (2020) Journal homepage: http://www.ijcmas.com The antagonistic efficacy of five different bio-agents viz., Trichoderma viride, Trichoderma harzianum, Trichoderma longibrachiatum, Pseudomonas fluorescens and Bacillus subtilis was tested against 25 isolates of Macrophomina phaseolina causing castor root rot by dual culture techniques under in vitro conditions. Variation in respect of growth inhibition of M. phaseolina was observed among the bio-agents as well as isolates. Among five bio-agents, significantly maximum mean growth inhibition (53.19 %) was recorded by T. viride followed by T. harzianum (49.81 %) while minimum growth inhibition (26.79 %) was recorded by P. fluorescens followed by B. subtilis (28.66 %). Among different 25 isolates of castor root rot pathogen, significantly maximum mean growth inhibition (35.31 %) was recorded of Mp-25 followed by Mp-7 (32.83 %) which was at par with Mp-10 (32.03 %), Mp-11 (31.98 %) and Mp-12 (31.98 %). Maximum growth inhibition of most of the isolates of M. phaseolina was observed by T. viride except Mp-4, 8, 16, 21 and 24 in which maximum growth inhibited by T. harzianum. Interaction effect of different bio-agents and isolates also showed significant variation in respect of per cent growth inhibition. Keywords Macrophomina phaseolina isolates, Castor root rot, Efficacy of bio- agents Accepted: 26 August 2020 Available Online: 10 September 2020 Article Info