Rizobakteri merupakan kelompok bakteri yang aktif mengkolonisasi akar tanaman, meningkatkan pertumbuhan dan mengendalikan patogen tanaman. Penelitian ini bertujuan untuk memperoleh isolat rizobakteri indigenous  terbaik dalam meningkatkan pertumbuhan kelapa sawit dan mengendalikan penyakit busuk pangkal batang di pre-nursery kelapa sawit secara in planta serta karakterisasi kemampuan antagonisnya secara in vitro. Penelitian bersifat eksperimental terdiri atas 3 tahap dengan menggunakan Rancangan Acak Lengkap (RAL): (1) Isolasi dan karakterisasi isolat rizobakteri indigenous  di Kabupaten Pasaman Barat, (2) Pengujian isolat rizobakteri indigenous  (RBI) sebagai plant growth promoting rihzobacteria (PGPR), dan untuk pengendalian G.boninense di pre-nursery kelapa sawit terdiri dari 29 perlakuan (27 isolat RBI, tanpa inokulasi G. boninense sebagai kontrol positif, dan inokulasi G. boninense sebagai kontrol negatif) dengan masing-masing 5 ulangan, serta (3) Pengujian aktivitas antagonisme isolat RBI terhadap G. boninense. Data dianalisis dengan sidik ragam, apabila berbeda nyata dilanjutkan dengan uji Least Significance Different (LSD) pada taraf 5%. Hasil penelitian menunjukkan diperoleh tiga isolat terbaik (R10 2.2, R9 2.1, dan R10 2.3) yang mampu meningkatkan pertumbuhan kelapa sawit dan menekan perkembangan penyakit busuk pangkal batang G.boninense secara in planta dan in vitro. ABSTRACT Rhizobacteria is a group of bacteria that actively colonize plant roots, increase growth and control plant pathogen. The objective of the research was to obtain indigenous rhizobacteria isolate (RBI) to increase growth and control basal stem rot on oil palm seedlings in in planta and characterize of antagonistic ability in in vitro. Experimental research consisted of 3 stages by using Completely Randomized Design (CRD): (1) Isolation of indigenous rhizobacteria in West Pasaman region, (2) Indigenous rhizobacteria isolate testing as a plant growth promoting rhizobacteria (PGPR) and to control of G. boninense on pre nursery of oil palm consisted of 29 treatments (27 RBI isolates, without G. boninense inoculation as positive control, and G. boninense inoculation as negative control) with 5 replications each. (3) Testing of RBI isolate antagonism activity towards G. boninense. Data were analyzed by variance, if the result significantly different, it was continued by using Least Significance Different (LSD) at 5% level. The results showed that best three isolates (R10 2.2, R9 2.1 and R10 2.3) were able to increase growth of palm oil and to suppress the development of G.boninense basal stem rot in in planta and in in vitro.