Research has been conducted in the Penan Village, District of Ampenan, Mataram City, Lombok Island, Indonesia. The study was conducted in a completely randomized design consisting of 4 treatments, namely treatment with Streptomyces sp. (S), treatment with Trichoderma sp. (T), treatment with a combination of Streptomyces sp. and Trichoderma sp. (ST), and without treatment biological agent (K). Applications of a biological agent were carried out before planting by soaking chili seeds and watering the rhizosphere of chili plants after two weeks of planting. Results showed that the compatibility test of the two biological agents were not inhibit each other. This showed that the two biological control agents were not influence each other so that they could be used together to control plant pathogens. Combination treatment (ST) showed the best results in delaying the incubation period of leaf spot disease of chili to 9.6 days and 74 days on anthracnose chilies disease. Combination treatment of biological control agents was able to reduce the intensity of leaf spot disease to 16.2% and 11.6% in anthracnose. The growth of the plants was the best by treatment of Streptomyces sp. and Trichoderma sp (ST) by proving the highest height of plants compared to other treatments.

Keywords : Biological Control Agent, Streptomyces sp., Trichoderma sp.