Scholarly Journal of Agricultural Science Vol. 5(1), pp. 8-15 January, 2015 Available online at http:// www.scholarly-journals.com/SJAS ISSN 2276-7118 © 2015 Scholarly-Journals Full Length Research Paper In-vitro evaluation of selected bio-control agents against foot and root rot pathogens of lentil Hoque, S. 1* , Sultana, N. 2 , Faruq, A.N. 3 , Bhuiyan, M.Z.R. 4 and Islam, N. 1 1 Student, Department of Plant Pathology, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh 2 Professor, Department of Plant Pathology, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh 3 Assistant Professor, Department of Plant Pathology, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh 4 Assistant Professor, Department of Plant Pathology, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh Accepted 20 December, 2014 An investigation was carried out to evaluate the six selected isolates of three bio-control agents against foot and root rot pathogens. The pathogens, Fusarium oxysporum and Sclerotium rolfsii were isolated from foot and root rot infected lentil seedlings. Four isolates of Rhizobium leguminosarum, one isolate of Pseudomonas fluorescens and one isolate of Trichoderma harzianum were used as bio-control agents. In dual culture method, highest zone of inhibition of F. oxysporum (57.37%) was measured against R. leguminosarum isolate 3 and isolate 4. In case of S. rolfsii, 80% and 37.85% inhibition zone were measured against P. fluorescens and T. harzianum, respectively. In paper towel and water agar test tube tests, seed treatment with all the bio-control agents showed significantly better germination than control. It also resulted in significant increase in shoot and root length that gave high vigor index. In paper towel test, minimum number of deed seeds (9.00), no abnormal and diseased seedlings were counted from R. leguminosarum treated seeds. In water agar test tube test, minimum number of deed seed (12.00) and abnormal seedlings (2.00) were counted from R. leguminosarum treated seeds. Here, no diseased seedling was found from T. harzianum treated seeds. Key words: Lentil, Foot and root rot, bio-control agents - Rhizobium, Pseudomonas, Trichoderma. INTRODUCTION Lentil (Lens culinaris) has a great impact in the world agriculture due to its high protein content and special capacity for fixing atmospheric nitrogen. In Bangladesh, lentil is second important pulse crop that is cultivated in an area of 1,54,655 ha and the yearly production is about 1,22,000 mt (BBS, 2009). Among the major diseases of lentil, foot and root rot is the most important one which is caused by soil borne fungi like Fusarium oxysporum, Sclerotium rolfsii and Rhizoctonia solani. It may cause upto 100% seedling mortality in the field (Begum, 2003). Though this disease can be chemically controlled but it causes environmental pollution, health hazards and also is not economical. Hence, biological control agents like Pseudomonas fluorescens, Rhizobium leguminosarum *Corresponding author e-mail: sanzidahoque_209@yahoo.com and Trichoderma harzianum can be used both for seed treatment and field application. Pseudomonas fluorescens can suppress the disease by it’s ability to utilize varied substrates under different conditions; short generation time and assists colonization of roots. Rhizobium spp. inhibit the growth of foot and root rot causal pathogens, decrease foot and root rot disease by producing volatile substances, fluorescent pigment, enzymes, chitinase, siderophore and hormone (Kibria and Hossain, 2002). This study has been undertaken to determine the efficacy of some bio-control agents against foot and root rot pathogens of lentil in the laboratory condition. MATERIALS AND METHODS The study was conducted at Plant Disease diagnostic