The experiment was conducted with three replication in randomized complete block design in field laboratory of Department of Agronomy, Bangaladesh Agricultural University, Mymensingh. Extracts of garlic (Allium sativum) and neem (Azadirachta indica), BAU-Biofungicide (Trichoderma based preparation) and Proud (Propiconazole) and Bavistin (Bavistin DF) were evaluated under field condition in controlling brown spot disease Bipolaris oryzae (Breda de Haan) Shoem of rice cv BRRI dhan28. Foliar spray of BAU-Biofungicide (2%) and Proud (0.1%) showed profound effect in marked reduction of disease severity. BAU-Biofungicide (2%) resulted grain yield 5785 kg/ha in the field and reduction in cost of production was found with benefit-cost ratio (BCR). BCR 2.78:1 was achieved in BAU-Biofungicide (2%) which is close to 2.87:1 in Proud (0.1%). Highest (98.00%) germination percentage was observed with BAU-Biofungicide (3%) as well as maximum (35.64%) increase of vigour index was found with Proud (0.1%) over control. BAU-Biofungicide and Proud were found to have in inhibiting seed borne fungi when they were applied as foliar spray. Trichoderma harzianum was associated with B. oryzae infected seeds and when kept for few days for incubation it overgrew B. oryzae.
Key words: BAU-Biofungicide, Bipolaris oryzae, benefit-cost ratio (BCR), disease severity, seed borne fungi, vigour index.