JOURNAL OF PURE AND APPLIED MICROBIOLOGY, APRIL 2014. Vol. 8(2), p. 973-978 * To whom all correspondence should be addressed. E-mail:umikay@upm.edu.my; lailanaherupm@gmail.com In vitro and In vivo Biocontrol Performance of Trichoderma harzianum Rifai on Ganoderma boninense Pat. Related to Pathogenicity on Oil Palm (Elaeis guineensis Jacq.) Laila Naher 1,2 , Umi Kalsom Yusuf 2 , Soon Guan Tan 3 , Shafiquzzaman Siddiquee 4 and M. Robiul Islam 5 1 Faculty of Agro Based Industry, Universiti Kelantan Malaysia,17600 Jeli, Kelantan. 2 Department of Biology, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan, Malaysia. 3 Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor Darul Ehsan, Malaysia. 4 Biotechnology Research Institute, Universiti Malaysia Sabah, Jalan UMS, 88400 Kota Kinabalu, Sabah, Malaysia. 5 Department of Agronomy and Agricultural Extension, University of Rajshahi, Rajshahi 6205, Bangladesh. (Received: 18 November 2013; accepted: 10 January 2014) Ganoderma boninense, causes basal stem rot disease in oil palm, which leads to severe losses to the palm oil industry. The antagonistic effect of Trichoderma harzianum on G. boninense (a causal pathogen for oil palm) was tested by in vitro and in vivo studies. T. harzianum inhibited the mycelia growth of G. boninense on in vitro plate assay experiment and in vivo on the glass house grown oil palm plants. During the in vivo experiment, at first time point after one month, G. boninense development was found in oil palm root tissues in control plants whereas in T. harzianum treated plants no disease symptoms were observed until at the end of the experiment. It is a broad spectrum approach to use T. harzianum to control G. boninense infection of oil palm. Key words: In vitro, In vivo, Biocontrol, Trichoderma, Ganoderma, Oil palm. Ganoderma boninense is a highly pathogenic fungus for oil palm, causing a disease called basal stem rot (Susanto et al., 2005). The disease is so destructive that it can affect thousands of hectares of oil palm plantation (Susanto et al., 2005). The disease was first detected in 1915 the Belgian Congo (Democratic Republic of congo), west Africa (Wakefield, 1920). In Malaysia, the disease was first recorded in 1931 on 25 years old oil palm plant (Arrifin et al., 2000). Ganoderma can infect in all stages of oil palm growth. The disease progress is slow but eventually every infected plant will die due to this disease. Usually, the disease spreads from root and then the fungus degrades specifically the lignin component of the wood then leaving the white cellulose exposed and finally collapse the plant (Sanderson et al., 2000). The use of biological control agents such as fungi or bacteria is considered important because they control the disease without causing any negative effect to the plant and environment. Trichoderma spp. is one of the most versatile soil borne fungus belongs to the filamentous class deuteromycetes with most strains adapted to an asexual life cycle (Harman, 2004). The rapidly growing fungus Trichoderma spp. has persistent conidia and broad spectrum substrate utilization. Therefore, it is very efficient competitors for nutrition and living space compared to other fungi, characteristic makes it is a good biocontrol agent (Hjeljord et al., 2000). Another characteristic ‘mycoparasitism’ also enhances its capability to become a good bicontrol