Abstract:In order to obtain biocontrol microorganism and agents those can efficiently and stably control the plant-parasitic nematodes, rhizosphere actinomycetes and endophytic bacteria were isolated and subjected for primary screening in vitro for their effects on mortality of Bursaphelenchus xylophilus. Secondary screening was evaluated for the control effect of the fermentation broth of the primary screened strains on root-knot nematodes via potted plantlet. Then those strains that had biocontrol activity were made into agent, the control effect of the single agent and their mixed agents were tested separately. From primary screening, 16 rhizosphere actinomycete and 4 endophytic bacteria secreting antinematode metabolite were isolated. In secondary screening, the fermentation broth of 2 actinomycete and 3 endophytic bacteria could obviously inhibit the increasing of the root-knot nematodes in tomato, and the inhibitory effect remained generally stable when the fermentation broth of actinomycete was mixed with that of endophytic bacterium and poured to the potted plantlet. But the biocontrol effects on root-knot nematodes with the combinations of agents from actinomycete and endophytic bacteria were lower than those of the single endophytic bacteria agent treatments. The maximum biocontrol effect in the experiment was reached by endophytic bacteria agents of BCM2 and CCM7, their inhibitory effect were 83.31% and 83.07%, respectively. The results indicated that endophytic bacteria agent has great application potential in preventing root-knot nematodes.