|In this study, biocontrol agents, derived from 4 screened microorganisms, for preventing the growth of ＂Phellinus noxius＂ which causes brown root rot disease were tested using simulations and field tests. The technology of a polymerase chain reaction (PCR) specific for ＂P. noxius＂, created in our laboratory, was used to monitor the control efficiency of the biocontrol agents against ＂P. noxius＂ infection. ＂Phellinus noxius＂ covered the entire PDA culture dish (at 9 cm in diameter) within 4 d in the control group; in contrast diameters of colonies ranged 0.62~7.8 cm in the test groups bearing the 4 screened biocontrol agents. These results revealed that all agents possessed control potential against ＂P. noxius＂ infection. Of these biocontrol agents, 2 showed the best control efficiency and persistency. The ＂P. noxius＂ stubs in moistened soil for 7 wk retained about 88.89 and 80% germ survival on cassia and banyan stubs in the simulated field test, respectively. Interestingly, ＂P. noxius＂ was inhibited when the soil was moistened with 0.5x, 1x, and 10x of biocontrol agent 2. In the actual field tests, we found that 1 Philippine ebony persimmon infected by ＂P. noxius＂ gradually grew a green leaf from the withered portion after treatment with biocontrol agent 2 for 8 wk, consistent with a decrease in the ＂P. noxius＂ population detected by the PCR. Likewise, detectable ＂P. noxius＂ was gradually reduced with treatment time with biocontrol agent 2 from Taiwanese and 20 flameinfected trees. Collectively, damage by ＂P. noxius＂ can be significantly ameliorated by the biocontrol agents examined in this study.