Judul: Pengelolaan Hama dan Penyakit Tanaman pada Budidaya Brokoli di Kabupaten Cianjur dan Nilai Ekonominya
Abstrak: Cultivation of broccoli is very susceptible to pest and disease infestation. In controlling plant pests and diseases, farmers usually use synthetic pesticides. There are only small number of farmers practicing integrated pest management (IPM) which is not giving negative effects to environment. This study was aimed to identify the pest control applied by broccoli farmers in Cianjur and to determine the economic value of the pest management. This research was carried out by conducting survey to 100 farmers by convenience sampling and to verify the type of pests and diseases observed in the field. The result of the study has shown that the main pests broccoli in Cianjur are Crocidolomia pavonana, Plutella xylostella, and Agrotis ipsilon, while the primary diseases are club root, black rot and Alternaria spots. All of broccoli farmers were spraying synthetic pesticides for controlling pests and diseases and 71% of them were combining the control technique with Trichoderma spp. and kaptan. The value of B/C ratio of the combination of control technique is 1.7 times bigger compared to the B/C ratio of pesticide only.
Keyword: broccoli, pests and disease control, B/C ratio

Judul: Pengelolaan Organisme Pengganggu Tanaman pada Budidaya Krisan (Chrysanthemum spp.) di Kabupaten Cianjur dan Nilai Ekonominya
Abstrak: Krisan merupakan salah satu tanaman hias komoditas hortikultura yang banyak diminati oleh masyarakat karena memiliki keindahan, estetika, dan nilai ekonomi yang tinggi. Kehadiran hama dan penyakit dapat menyebabkan penurunan kuantitas maupun kualitas produksi krisan di Cianjur, sehingga diperlukan adanya suatu tindakan pengendalian yang dapat mencegah penurunan produksi tersebut. Penelitian ini bertujuan mengetahui praktik pengelolaan hama dan penyakit terkini pada budidaya krisan, faktor yang memengaruhinya, dan menghitung nilai ekonominya. Metode penelitian yang dilakukan meliputi wawancara petani, pengamatan OPT di lapangan, dan analisis data. Hama utama pada tanaman krisan adalah lalat pengorok daun (Liriomyza huidobrensis) dan trips (Thrips parvispinus). Sedangkan, penyakit utamanya adalah karat putih (Puccinia horiana). Untuk mengendalikan serangan hama dan penyakit tersebut, hampir seluruh petani responden (99%) menggunakan hanya pestisida sintetis dan sisanya (1%) menggunakan sticky trap disamping pestisida sintetis. Sebagian besar petani (89%) melakukan pencampuran berbagai jenis pestisida dan hanya sebagian kecil (11%) yang hanya menggunakan satu jenis pestisida sintetis. Faktor kegagalan panen merupakan alasan terpenting bagi petani yang kurang berminat terhadap cara pengendalian lain selain pestisida sintetis. Penggunaan satu jenis pestisida sintetis dalam mengendalikan OPT dapat memberikan efisiensi 3 kali lipat dari pada melakukan pencampuran lebih dari satu jenis pestisida sintetis.
Keyword: tanaman krisan, nilai ekonomi, hama dan 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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