The objective of this research was to investigate the potential antagonism of actinomycetes isolates against Helminthosporium maydis fungus causing southern leaf blight on Maize. The antagonistic activity of 6 actinomycetes isolates toward H. maydis fungus were examined in the Laboratory conditions with 4 replications. The results showed that 3 actinomycetes isolates of TÔ-VL11d, KS-ST6b and BM-VL12 had highest antagonistic effect on H. maydis with radius of inhibition zones reache 11.00 mm, 11.40 mm, 9.60 mm, respectively and antagonistic efficacy of 53.93%, 53.13%, 51.27% at 10 days after testing. On the other hand, the efficiency of 6 actinomycetes isolates in prevention of H. maydis mycelial growth was conducted with 5 replications. The results indicated that BM-VL12 isolate had highest reduction on mycelial growth of H. maydis fungus with the colony diameter reache 45.6 mm at 7 days after inoculation.

Keywords: Actinomycetes, Helminthosporium turcicum, Maize, prevention of mycelia growth, southern leaf blight.