Root rot disease caused by Phythophthora sp. fungus is one of the important diseases on jackfruit because it affects productivity and income of farmers growing Jackfruit. The objective of this research was to examinate the actinomycetes able to control with Phythophthora sp. fungus causing root rot disease on Jackfruit. The cellulase activity of 5 actinomycetes isolated (BM3-VL, BM5-VL, BM7-VL, CT12-HG and CB4-TG ) were examined with 4 replications under laboratory condition. The results indicated that, CT12-HG isolate has expressed the cellulolytic activity, with the cellulose lyses halo radius of 28.8mm at 7 days after testing. The biocontrol ability of 2 actinomycete isolates (BM5-VL and CT12-HG) was tested with 4 replications under net-house condition. The results indicated that CT12-HG isolate which were applied twice (2 days before and 2 days after pathogen inoculation) gave the highest ability to control the disease through low ratio of root rot (27.68%) and high efficiency of disease reduce (65.24%) and were not different signification with the chemical treatment at 43 days after inoculation. The results of this study will be the basis for further researchs to find the biological products that are capable of controlling jackfruit disease and are environmentally friendly.

Keywords: Actinomycetes, cellulose, root rot disease on Jackfruit, Phytophthora sp.