Judul: Kelimpahan Hama dan Musuh Alami pada Pertanaman Kacang Hijau (Vigna radiata L.)
Abstrak: Mungbeans are a legume crop widely cultivated after soybeans and peanuts in Indonesia. One limiting factor in the production of mungbeans is a pest. Mung bean plants associated with 85 species of pests. This study aims to determine abundance of pest and natural enemies in mungbean field. The study was conducted from March to May 2012. The research was conducted in a plantation of mungbeans at Situgede village, Bogor, West Java. Identification carried out at the Laboratory of Insect Ecology, Department of Plant Protection, Faculty of Agriculture, Bogor Agricultural University. Pests are observed during the planting of mung beans was Ophiomya phaseoli attacking seedlings phase (8-21 day after planting (DAP)). Aphis craccivora, Empoasca spp., and Thrips spp. were found in the crop from vegetative to generative phase (21-70 DAP). Pests of the generative phase (35-70 DAP) were Riptortus linearis, Nezara viridula, and Maruca testulalis. While natural enemies found were Coccinellidae, Sycanus annulicornis, Syrphidae, spiders and Paederus fuscipes
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Judul: Major Pests and Diseases of Mungbeans (Vigna radiata L.) in Batursari Village, Batangan District, Pati Regency
Abstrak: Kacang hijau merupakan salah satu tanaman penting yang bernilai ekonomi di Indonesia. Namun, kehadiran organisme pengganggu tanaman (OPT) dapat menurunkan produktivitas kacang hijau. Penelitian ini bertujuan memberi informasi mengenai jenis-jenis OPT dan musuh alami pada tanaman kacang hijau, serta mengetahui hama dan penyakit yang dominan di lokasi pengamatan tersebut. Pengamatan dilakukan mulai dari awal pertumbuhan hingga menjelang panen. Penentuan tanaman contoh menggunakan metode diagonal dengan membagi lahan menjadi 5 petak, masing-masing petak diambil 20 tanaman contoh yang dipilih secara acak. Inventarisasi hama dan penyakit meliputi gejala serangan, populasi, kejadian dan keparahan penyakit yang terjadi di lapangan. Hama-hama pada tanaman kacang hijau di Desa Batursari, Kecamatan Batangan, Kabupaten Pati adalah lalat bibit (Ophiomyia phaseoli), kutudaun (Aphis craccivora), thrips, wereng daun (Empoasca sp.), penjalin daun (Lamprosema indicata), kepik pengisap polong (Piezodorus hybneri, Riptortus linearis), penggerek polong (Maruca testulalis), selain itu terdapat hama lain yang tingkat serangan dan populasinya masih rendah yaitu belalang, kutu kebul, kumbang, ulat grayak dan ulat bulu. Penyakit pada tanaman kacang hijau di lokasi tersebut yaitu bercak daun cercospora. Musuh alami pada tanaman kacang hijau di lokasi tersebut yaitu kumbang coccinellidae, laba-laba oxyopidae, dan lalat dolichopodidae. Hama penyakit tanaman penting pada tanaman kacang hijau di lokasi tersebut yaitu O. phaseoli dengan intensitas serangan mencapai 17%, A. craccivora dengan populasi mencapai 9,14 serangga/tanaman, M. testulalis dengan intensitas serangan mencapai 29,31%, serta bercak daun cercospora dengan insidensi penyakit 100% dan keparahan penyakit mencapai 37,11%., Mungbean is one of the economic important crops in Indonesia. However, plant pests and diseases can reduce the mungbeans production. This study aims to provide information about the diversity of plant pests and diseases and natural enemies of mungbeans, as well as to find out the dominant pests and diseases at the observation area. Pests and diseases were observed weekly, started at seedling growth stage to harvesting growth stage. Determination of sample plants using the diagonal method by dividing the field into 5 plots, each plot taken 20 sample plants selected at random. Inventory pests and diseases includes symptoms, population, incidence and severity of diseases that occur in the field. The pests of mungbeans in Batursari, Batangan District, Pati Regency were bean flies (Ophiomyia phaseoli), aphids (Aphis craccivora), thrips, leafhoppers (Empoasca sp.), leaf rollers (Lamprosema indicata), pod bugs (Piezodorus hybneri, Riptortus linearis), pod borers (Maruca testulalis), besides that there were other pests with low population, namely grasshoppers, whiteflies, beetles, armyworms and caterpillars. The disease of mungbeans in that field was cercospora leaf spot. The natural enemies in that field were coccinellids, oxyopid spiders, and dolichopodid flies. The major pests and diseases of mungbeans in that field were O. phaseoli with incidence of 17%, A. craccivora with population of 9,14 insects/plant, M. testulalis with incidence of 29,31%, and cercospora leaf spot with incidence of 100% and disease severity of 37,11%.
Keyword: cercospora, incidence, Ophiomyia phaseoli, population

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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