Judul: Hama dan penyakit tanaman buah naga (Hylocereus sp.) serta budidayanya di Yogyakarta
Abstrak: Dragon fruit (Hylocereus sp.) has been introduced to Indonesia recently and became a commercial crop cultivated in this country. The plant, which belongs to family of Cactaceae (cactus), is native to Mexico, Central, and South America. There are no many reports about significant losses due to pests and diseases of the plant in Indonesia, or even in other countries. However, it is potential that pests and diseases can become problem in the future as the plant become widely grown in Indonesia. The objective of this research is to gather information about pest and disease occurrences found in dragon fruit and its cultivation in Yogyakarta. The research methods including interview with farmers, observation, and sampling of the pests and diseases at six dragon fruit orchards, field, and laboratory identification of the causal agents, and data processing. The pests found in dragon fruit were mealy bugs (Hemiptera:Pseudococcidae) species Pseudococcus jackbeardsleyi, Ferrisia virgata, and Planococcus sp.; aphids (Hemiptera:Aphididae) species Aphis gossypii., Branchycaudus helichrysi, and Toxoptera odinae; ants (Hymenoptera:Formicidae) species Oecophylla sp., Camponotus sp., Euprenolepis sp., and Polycharis sp.; grasshoppers (Orthoptera:Acrididae) species Valanga sp., Oxya sp., and Atractomorpha sp.; mite (Acarina:Tetranycidae); snail (Acathina fulica); and birds. Chickens are not considered as a pest, however, they can cause severe damage on fruit if they are allowed to present in the orchard. Diseases found in dragon fruit were algae red rust (Cephaleuros sp.), vine orange spot (Fusarium sp.), white vine (Botryosphaeria sp. and Phomopsis sp.), stem blight (Helminthosporium sp.) and anthracnose (Colletotrichum sp.), Dothiorella spot, brownish stem rot, stem yellowing, fruit rot (Colletotrichum sp. and Helminthosporium sp.) fruit orange spot (Alternaria sp.). A black spot disease on stem has not been identified yet. Pests and diseases have not been controlled in particular system, probably because their occurrences have not resulted in a significant loss.
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Judul: Pests and Diseases of Dragon Fruit (Hylocereus sp.) with Lamp Cultivation System in Banyuwangi Regency
Abstrak: Buah naga (Hylocereus sp.) merupakan salah satu komoditas hortikultura yang penting dan banyak dibudidayakan di Indonesia. Kehilangan hasil akibat hama dan penyakit pada tanaman buah naga belum banyak dilaporkan di Indonesia khususnya di Kabupaten Banyuwangi. Penelitian ini bertujuan mengamati hama dan penyakit tanaman buah naga dengan sistem budi daya berlampu pada perkebunan buah naga di Kabupaten Banyuwangi. Penelitian dilakukan dengan pengamatan hama dan penyakit secara berkala dan wawancara. Pengamatan lalat buah dilakukan dengan pemasangan perangkap methyl eugenol. Pengamatan dilakukan pada delapan lahan buah naga di Kecamatan Pesanggaran dan Siliragung. Identifikasi hama dan penyakit dilakukan dengan membandingkan gejala yang teramati di lapangan dengan literature yang sesuai. Hama pada tanaman buah naga yang paling banyak ditemukan di lahan pengamatan adalah lalat buah, semut, kutuputih, kutudaun, bekicot, dan tikus. Penyakit yang paling banyak ditemukan adalah putih sulur, busuk batang, kanker batang, antraknosa, bercak oranye, dan kuning sulur., Dragon fruit (Hylocereus sp.) is an important horticultural commodity that widely cultivated in Indonesia. Yield losses due to pests and dragon fruit diseases have not been reported in Indonesia, especially in Banyuwangi Regency. This research aims to observe the pests and diseases of dragon fruit cultivatedusing lamps in Banyuwangi Regency. The research was conducted by direct observation and interview, Observation and trapping fruitflieswere carried out on eight dragon fruit fields in the Pesanggaran and Siliragung Districts. Simple identification of pests and diseases is carried out by comparing the observed pest and diseases with the literature. . The most frequent pests observed in dragon fruit plantation were fruitflies, ants, mealybugs, aphids, snails, and rat. Then the most observed diseases symptoms were white tendrils, stem rot, stem cancer, anthracnose, orange spots, and yellow tendrils.
Keyword: buah naga, budidaya berlampu, hama, penyakit, dragon fruit, lamps-added cultivation, pests, diseases

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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