The effectiveness of eight bacteria formulations of Bacillus subtilis (Ehrenberg) Cohn. on maydis leaf blight (Bipolaris maydis (Nisik. & Miyake) Shoemaker) in corn (Zea mays L.)

Utilization of biological control agents (BCA) against plant pathogens is an important component of integrated pest control management. Bacillus subtilis (Ehrenberg) Cohn as plant growth promoting rhizobacteria (PGPR) bacteria with one of its functions namely bioprotector has been shown to suppress the attack of several kinds of pathogens. This study aimed to test the effectiveness of some isolates of B. subtilis formulated in the form of flour to control maydis leaf blight (Bipolaris maydis (Nisik. & Miyake) Shoemaker) in corn (Zea mays L.). The experiment was conducted in the plant pathology laboratory with co-cultivation test and in the greenhouse of Indonesia Cereals Research Institute (ICERI) from February 2015 to December 2016. In the laboratory test, test for diffusible toxic metabolite(s) was done by agar co-cultivation test method. In the green house experiments, the treatments were arranged in a completely randomized design consists of 10 treatments; i.e. Seed treatments and spraying suspension of B. subtilis formulation BS-TLB1, BS-BJ6, BS-M3, BS-TM4, BS-BNt4, BS-BNt5, BS-BNt6, BS-BNt8 and two controls (K1 with the use of synthetic fungicides and K2 with steril destiled water). Data collected were percentage of inhibition of BCA(s), percentage of seed germination, plant height and disease incidence of maydis leaf blight. The results showed that formulation of B. Subtilis TM4 and BJ6 performed the best in co-cultivation test, application of B. subtilis formulations by means of seed treatment can stimulate plant growth and suppress maydis leaf blight incidence. Spraying plants with suspension of B. subtilis a formulation was more effective in suppressing maydis leaf blight incidence than the seed treatment method. Formulation of B. subtilis TM4 showed the best efficacy in promoting plant growth and its ability to suppress the maydis leaf blight incidence either through seed treatment and spraying the suspension.