BIODIVERSITAS ISSN: 1412-033X Volume 21, Number 5, May 2020 E-ISSN: 2085-4722 Pages: 1935-1939 DOI: 10.13057/biodiv/d210521 Effectiveness of biological control of Trichoderma harzianum on soybean leaf rust disease and the production in West Papua Lowland, Indonesia EKO AGUS MARTANTO 1 , ADELIN E. TANATI 1 , SAMEN BAAN 2 , HERMAN R. TATA 3 , AGUSTINUS MURDJOKO 4, 1 Laboratory of Plant Pests and Diseases, Faculty of Agriculture, Universitas Papua. Jl. Gunung Salju, Amban, Manokwari 98314, West Papua, Indonesia 2 Laboratory of Soil, Faculty of Agriculture, Universitas Papua. Jl. Gunung Salju, Amban, Manokwari 98314, West Papua, Indonesia 3 Center for the Assessment and Application of Technology. Jl. Brigjen Abraham O. Atururi, Manokwari 98135, West Papua, Indonesia 4 Faculty of Forestry, Universitas Papua. Jl. Gunung Salju, Amban, Manokwari 98314, West Papua, Indonesia.  email: agustinus.murdjoko.papua@gmail.com Manuscript received: 4 March 2020. Revision accepted: 12 April 2020. Abstract. Martanto EA, Tanati AE, Baan S, Tata HR, Murdjoko A. 2020. Effectiveness of biological control of Trichoderma harzianum on soybean leaf rust disease and the production in West Papua Lowland, Indonesia. Biodiversitas 21: 1935-1939. This study aims to evaluate the application of Trichoderma harzianum in leaf rust disease on soybean and its production. The study was conducted for three months starting from May to July 2017, at Residential Unit 11th Sidey Subdistrict, Manokwari District, West Papua Province, Indonesia. This study was designed using Factorial Complete Randomized Design consisting of two treatment factors and repeated three times. There was no treatment of pathogen inoculation in the field. The tested varieties had a different response to plant height. Burangrang, Grobogan, Dena-1, Anjasmoro, and Detam-1 varieties were categorized as moderate resistant varieties. The Trichoderma harzianum application should be applied in the whole crops of soybean to control environmentally the leaf rust disease. Seeds weight per plot for Dena-1 variety was higher compared to other varieties. The combination of Detam-1 varieties with Trichoderma treatment 2 times resulted in increased production. Keywords: Leaf rust, production, soybean, Trichoderma harzianum, West Papua INTRODUCTION Soybean is one of the important crops in Indonesia in which foods made of soybean contain high carbohydrates and isoflavones which is an anticancer (Astawan and Fabrinda 2009). Moreover, the high protein content at the level of 30.3-34.6% can be used as an alternative protein source (Yuwono et al. 2012). The development of foods and feeds industry with soybean as their raw materials is followed by the population growth causing the demand for soybean in Indonesia increases significantly. The development of foods and feeds industry with soybean as their raw materials is followed by the population growth causing the demand for soybean in Indonesia to increase significantly (Swastika et al. 2009). Papua has abundant local food stock potency, particularly soybeans as a food source. Statistical data indicates that the soybean production for Manokwari reaches 1.1 ton/ha (Anonimous 2017). The total population of Papua is about 2.2 million with a population growth of 3.14% per year. The increasing population number has caused increased food demand. Therefore, soybean production increases, either by intensification or extensification should be constantly performed to reduce the dependence on imported soybeans (Sudjudi et al. 1989). Sidey Makmur Village (Residential Unit 11 th ) is one of the development centers for soybean commodities in Manokwari with specific advantages that are not found in other regions in Indonesia, particularly the planting period 4 times in a year. This superiority is a potency that can increase yield productivity, but the obtained product is not as expected. One of the obstacles in increasing soybean productivity is pests and diseases attack. The important disease of soybean plants is leaf rust caused by Phakopsora pachyrhizi. Leaf rust disease, an important disease in soybean, occurs during summer (Semangun, 2008: Sumartini 2010: Soesanto 2015). Production loss due to leaf rust disease could reach 40-90% in Indonesia (Sudjono et al. 1985). Most of the planted varieties in Sidey Subdistrict are Anjasmoro variety. According to a description from Baliktabi Malang Indonesia, Anjasmoro variety resistance to rust is moderate. The planting of Anjasmoro variety continually will produce a new pathogenic race that can break the resistance of the variety. Therefore, an alternative variety is needed. Biological control of diseased soybean plants can be done by utilizing microbes that are antagonistic to pathogenic fungi (Agrios 1996). Plant diseases control using biological agents can reduce chemical pesticide use. One of the antagonistic biological agents and can control the disease is Trichoderma harzianum. T. harzianum has ability as biological control with a wide spectrum in various crop plants. Several studies indicated that the antagonistic agent can reduce the plant diseases development from various pathogen attacks such as Elsinoe batatas in sweet potatoes (Martanto et al. 2015), Verticillium sp. in Strawberries (Suryawan et al. 2017), and Fusarium oxysporum in tomatoes (Fitrianingsih et al.