The research was conducted in Plant Protection Department, Cantho University and the objective of this research was to examinate the actinomycetes isolates able to antagonize with Fusarium solani fungus causing rot root disease on Pepper. The antagonistic ability against F. solani fungus of 14 actinomycetes isolates was determined with 5 replications in laboratory condition. The results found that 4 isolates VT4.CT, LM6.HG, CM7.AG and HB2.BL could reduce mycelia growth of fungus with high radiuses of inhibition zones reaches 15.00 mm, 13.5 mm, 7.25 mm and 6.25 mm, respectively and high of antagonistic efficacy 57.22%, 53.33%,  44.44% and 46.67%, respectively at 6 days after inoculation. On the other hand, the ability of inhibiting conidia germination of F. solani by 4 actinomycetes isolates (VT4.CT, LM6.HG, CM7.AG and HB2.BL) was examined in laboratory condition with 4 replications. The result indicated that 2 isolates, LM6.HG and CM7.AG have the highest inhibition effecicacy with the lowest rate’s conidia germination reaches 35.50% and 35.25%, respectively at 48 hours after co-inoculation. Beside, the ability of inhibiting sporulation of F. solani by these actinomycetes isolates was checked in laboratory condition with 5 replications. The result showed that 2 isolate, LM6.HG and CM7.AG have the highest inhibition effecicacy with the lowest log conidia concentration reaches 8.19 and 8.17, respectively at 7 days after testing.

Keywords: Actinomyces, conidia germination, Fusarium solani, rot root disease on peper.