Two hundred and six bacterial isolates were obtained from leaf, flower and stem of three healthy plants,Euphorbia pulcherrima Willd,Pyrethrum cinerariifolium Trev. andHeracleum candicans Wall. The nematicidal activity experiment showed that a total of 92 isolates displayed activity againstCaenorhabditis elegans (Maupas) Dougherty, and 70 isolates resulted active againstBursaphelenchus xylophilus (Steiner & Buhrer) Nickle. Strain LCB-3 exhibited the strongest nematicidal activity against both two nematodes. According to the 16S rDNA, the strain LCB-3 was identified asBrevundimonas diminuta. Based on bioassay-guided fractionation, a nematicidal metabolite (R)-(−)-2-ethylhexan-1-ol was obtained from LCB-3. The median lethal concentrations (LC50) of the compound were 542.0 mg l−1 againstC. elegans and 168.1 mg l−1 againstB. xylophilus 48 h after treatment.