Judul: Inventarisasi Hama dan Penyakit pada Pembibitan Tanaman Eucalyptus di Sentra Pembibitan 2 PT RAPP, Kabupaten Pelalawan, Riau
Abstrak: Perkembangan industri pulp dan kertas di Indonesia terus meningkat dari tahun ke tahun sehingga perlu adanya teknologi dan bahan baku yang cukup serta memadai. Bahan baku yang umumnya digunakan berupa jenis kayu hardwood yang telah dipersiapkan di area Hutan Tanaman Industri (HTI). Tanaman Eucalyptus sp. merupakan salah satu jenis tanaman prioritas yang dikembangkan dalam pengelolaan HTI yang diperuntukkan sebagai kayu serat. Salah satu masalah yang dapat mengganggu pertumbuhan tanaman dan mengakibatkan kerugian adalah serangan dari organisme pengganggu tanaman (OPT). Dalam beberapa kasus, serangan penyakit pada tanaman dapat mengakibatkan terhambatnya pertumbuhan tanaman, menurunnya kualitas kayu, bahkan kematian tanaman. Penelitian bertujuan mengetahui jenis-jenis hama dan penyakit, serta budi daya tanaman Eucalyptus dari sampel bibit bergejala yang diambil dengan metode purposive sampling di Sentra Pembibitan 2 PT RAPP, Kecamatan Pangkalan Kerinci, Kabupaten Pelalawan, Riau. Identifikasi patogen dilakukan dengan membandingkan hasil pengamatan gejala serta tanda di lapangan dan laboratorium dengan literatur. Inventarisasi hama dilakukan dengan studi literatur berdasarkan data hama ditemukan yang telah tersedia. Penyakit yang menyerang bibit Eucalyptus adalah bercak daun Quambalaria, bercak daun dan batang Cylindrocladium, bercak daun Kirramyces, layu pucuk dan daun Rhizoctonia, dan hawar daun Xanthomonas. Hama yang ditemukan menyerang bibit tanaman Eucalyptus, yaitu ulat penggulung daun (Strepsicrates macroptena), tungau, kutu kebul (eucalyptus whitefly), thrips (Thrips autralis), wereng, kutu daun, dan Helopeltis theivora., The development of the pulp and paper industry in Indonesia continues to increase from year to year, which requires adequate technology and raw materials. Raw materials that are generally used are hardwood species that have been prepared in the Industrial Plantation Forest (HTI) area. Eucalyptus sp. is one of the priority plant species developed in HTI management which is intended as fiber wood. One of the problems that can interfere with plant growth and cause losses is the attack of plant pest organisms (OPT). In some cases, disease attacks on plants can result in inhibition of plant growth, decreased wood quality, and even plant death. This study aims to determine the types of pests and diseases, as well as the cultivation of Eucalyptus from symptomatic seedling samples taken by purposive sampling method at PT RAPP Nursery Center 2, Pangkalan Kerinci District, Pelalawan Regency, Riau. Pathogen identification was carried out by comparing observations of symptoms and signs in the field and laboratory with the literature. Pest inventory was conducted by literature study based on available pest data. Diseases that attack Eucalyptus seedlings are Quambalaria leaf spot, Cylindrocladium leaf and stem spot, Kirramyces leaf spot, Rhizoctonia shoot and leaf wilt, and Xanthomonas leaf blight. Pests found attacking Eucalyptus seedlings were leafroll caterpillars (Strepsicrates macroptena), mites, whitefly (eucalyptus whitefly), thrips (Thrips autralis), leafhoppers, aphids, and Helopeltis theivora.
Keyword: Eucalyptus sp., industrial forest plantations, pathogens, diseases

Judul: Inventory Disease on Acacia crassicarpa Cunn Ex Benth at Kerinci Central Nursery 1 and Pelalawan Estate PT RAPP Pelalawan District Riau
Abstrak: Acacia crassicarpa merupakan salah satu tanaman berkayu yang digunakan untuk pembuatan pulp dan kertas. Hutan tanaman industri (HTI) PT. Riau Andalan Pulp and Paper (RAPP) merupakan salah satu HTI yang membudidayakan tanaman A. crassicarpa. A. crassicarpa dibudidayakan secara monokoltur dan tumbuh baik meskipun di lahan kritis. Penyakit tanaman merupakan salah satu masalah penting di perkebunan Akasia. Infeksi patogen dapat menyebabkan gangguan fisiologis yang mempengaruhi pertumbuhan tanaman dan kualitas kayu. Penelitian ini bertujuan untuk mengamati dan mengidentifikasi patogen yang menginfeksi A. crassicarpa di PT. RAPP. Pengamatan penyakit dilakukan di empat lahan selama 4 bulan, dimulai dari Januari sampai Mei 2022 di Kebun Pelalawan dan Sentral Pembibitan 1 PT RAPP Pangkalan Kerinci, Kabupaten Pelalawan, Provinsi Riau. Pengambilan sampel menggunakan metode purposive sampling. Tahap identifikasi penyakit dilakukan di laboratorium PT RAPP. Patogen penyebab diidentifikasi berdasarkan gejala visual dan bentuk mikroskopisnya. Penyakit bibit A. crassicarpa adalah layu daun yang disebabkan oleh Rhizoctonia sp., sedangkan penyakit pada tanaman adalah bercak daun yang disebabkan oleh Pestalotiopsis sp. dan Passalora perplexa, serta hawar daun yang disebabkan oleh Xanthomonas campestris pv. acaciae. Faktor yang mempengaruhi infeksi patogen di lapangan antara lain curah hujan, suhu, dan kelembaban., Acacia crassicarpa is a woody plant used for pulp and paper production. Industrial plantation forest (HTI) PT. Riau Andalan Pulp and Paper (RAPP) is one of the HTI plantations that cultivates A. crassicarpa plants. A. crassicarpa is cultivated in monoculture and grows well even on critical land. Plant disease is one of the important problems in Acacia plantations. Pathogenic infections can cause physiological disturbances that affect plant growth and wood quality. This study aims to observe and identify the pathogens that infect A. crassicarpa in PT. RAPP. Disease observations were carried out in four fields for 4 months, starting from January to May 2022 at the Pelalawan Garden and Central Nursery 1 PT RAPP Pangkalan Kerinci, Pelalawan Regency, Riau Province. Sampling using purposive sampling method. The disease identification proses was conducted at PT RAPP laboratory. The causative pathogen is identified based on its visual symptoms and microscopic appearance. Seedling disease of A. crassicarpa is leaf wilt caused by Rhizoctonia sp., while plant diseases were leaf spot caused by Pestalotiopsis sp. and Passalora perplexa, and leaf blight caused by Xanthomonas campestris pv. acaciae. Factors that affect disease infections in the field include rainfall, temperature, and humidity.
Keyword: Acacia crassicarpa, hutan tanaman industri, patogen, penyakit

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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