Azospirillum sp. and Streptomyces sp. is a potential microbes that can be used as biological control agents for Fusarium oxysporum f.sp cepae (FOCe) in shallot. The use of Azospirillum sp. and Streptomyces sp. singly has been studied, but the combined use has not been studied much. This study aims to determine the compatibility and effectiveness of Azospirillum sp. and Streptomyces sp. in controlling moler and shallot growth. The research consisted of an in vivo study (planting in polybags) and an in vitro study (compatibility tests and antagonism tests). The in vivo study was conducted with a nonfactorial Randomized Complete Block Design (RCBD) with five treatments, that is plants inoculated with FOCe (without biological control agents, Azospirillum sp., Streptomyces sp., Azospirillum sp. + Streptomyces sp., and fungicides). The in vivo test was conducted by dual culture method that is growing two microbes on the same petridish. The variables observed in the in vitro test were compatibility index and inhibition. The data were analyzed using analysis of variance (ANOVA) with a level of 5%. If there is a significant effect, then continued with Duncan’s Multiple Range Test (DMRT) at the 5% level. The results of the study affected the incubation period, disease intensity, effectiveness of disease suppression (EPP), infection rate, LBKPP, plant height, and weight of fresh stover. In vitro research showed that the bacterium Azospirillum sp. and Streptomyces sp. are compatible and do not inhibit each other, with a compatibility index of 0.97 and 0.91. The antagonism test performed showed Streptomyces sp. has a higher inhibition of 52.96%.
