Aplikasi jamur antagonis Trichoderma spp. untuk mengendalikan jamur Ganoderma sp. penyebab busuk akar di pertanaman acacia mangium

Penyakit busuk akar yang disebabkan oleh Ganoderma sp. menjadi persoalan penting bagi produktivitas Hutan Tanaman Industri (HTI) Acacia mangium. Tindakan pengendalian Ganoderma sp. perlu dilakukan menggunakan metode-metode yang eknomis dan ramah lingkungan. Sebagai salah satu komponen pengendalian penyakit terpadu, penggunaan agen hayati Trichoderma spp. perlu dikaji lebih lanjut. Penelitian ini bertujuan untuk mengetahui: (1) efektivitas Trichoderma spp. yang diaplikasikan di persemaian untuk mengendalikan Ganoderma sp. di pertanaman A. mangium, dan (2) interaksi antara isolat Trichoderma spp. yang diaplikasikan dengan isolat alami Trichoderma spp. hasil isolasi dari lapangan. Trichoderma spp. isolat T13 dan T62 dalam bentuk formulasi pelet diaplikasikan sebanyak lima butir pada setiap semai A. mangium, selanjutnya semai A. mangium ditanam di lapangan. Pada umur tanaman enam dan 12 bulan, dihitung tingkat serangan Ganoderma sp. dengan intensitas sampling (IS) 100%. Selain itu, diambil sampel tanah dari sekitar tanaman dengan IS 20% untuk mengidentifikasi keberadaan isolat T13 dan T62 serta untuk mengetahui sifat kimia sampel tanah. Hasil identifikasi melalui pengamatan makroskopis dan mikroskopis serta uji dual culture mengindikasikan keberadaan Trichoderma spp. isolat T13 dan T62 pada lokasi penelitian. Tingkat serangan Ganoderma sp. terendah pada pertanaman A. mangium umur 12 bulan ditemukan pada aplikasi T62 (2,67%), diikuti oleh kontrol (3,83%) dan T13 (4,83%). Plot-plot perlakuan T62 menunjukkan kerapatan koloni total Trichoderma spp. yang lebih tinggi (3,20x105/ml) dibandingkan T13 (2,79x105/ml) dan kontrol (2,65x105/ml). Pada media Potato Dextrose Agar (PDA), isolat T62 menunjukkan daya hambat terhadap Ganoderma sp. yang lebih lebih baik (95,91%) dibandingkan T13 (91,63%). Pada media Soil Agar (SA), daya hambat T62 relatif sama (70,70%) dengan T13 (70,52%). Pertumbuhan isolat T62 pada media PDA sampai hari ke-3 lebih baik (51,13 cm2) dibandingkan T13 (44,36 cm2). Selain itu, pertumbuhan, T62 pada media SA sampai hari ke-6 juga lebih baik (65,49 cm2) dibandingkan T13 (36,35 cm2). Interaksi antar Trichoderma spp. isolat T13 atau T62 dengan beberapa isolat Trichoderma spp. lainnya hasil reisolasi diketahui terjadi melalui kompetisi nutrisi dan ruang tumbuh. Dari hasil penelitian ini, diduga aplikasi isolat T62 bersinergis dengan Trichoderma spp. yang telah ada di lapangan untuk menghambat Ganoderma sp. Root rot disease caused by Ganoderma sp. has become a significant problem in the productivity of industrial forest plantations of Acacia mangium. Ganoderma sp. must be controlled with environmentally friendly measures, such as Trichoderma spp. which has already been proven in this field. The objectives of this study were (1) to as certain the effectiveness of Trichoderma spp. which was applied in nurseries to control Ganoderma sp. in plantations of A. mangium, and (2) to identify interactions between isolates of Trichoderma spp. which were applied deliberately, and naturally occurring Trichoderma spp. isolates in the field. Trichoderma spp. isolates T13 and T62 in pellet form were applied in a ratio of five pellets to each A. mangium seedling, following which the A. mangium seedlings were planted in the field. At the ages of six and twelve months, the level of attack by Ganoderma sp. was counted at sampling intensity of 100%, and soil samples were taken from around the plantings with a sampling intensity of 20% in order to identify the the presence of isolates T13 and T62, as well as to identify the chemical properties of the soil. The results of identification through macroscopic and microscopic observation as well as dual culture tests, point back to isolates which appear to be T13 and T62. In addition, results of the study showed that for 12-months old A. mangium, the use of applications of T62 lead to a lower level of attack by Ganoderma sp. in plantations of A. mangium (2,67%) compared to applications of T13 (4,83%) and the control (3,83%). Plot by plot, plantations to which T62 had been applied showed a total density of colonies of Trichoderma spp. which was higher (3,20x105/ ml) than for applications of T13 (2,79x105/ml) and the control (2,65x105/ml). In the case of PDA medium, T62 isolate demonstrated a better prevention effect against Ganoderma sp. (95,91%) compared to T13 (91,63%), while with SA medium, T62 showed a relatively similar effect to T13 (70.70% cf 70,52%). Growth of T62 isolate in PDA medium up to the third day was better (51,13 cm2) than that of T13 (44,36 cm2) and also with SA medium up to the sixth day, T62 was better (65,49 cm2) than T13 (36,35 cm2). Interaction between Trichoderma spp. isolates T13 and T62 and several other isolates of Trichoderma spp. indicated there was competition for both nutrition and growing space. Application of T62 isolate synergised with Trichoderma spp. in soil which has high growth capacity can increase the ability to resist Ganoderma sp.