Judul: Damage Intensity of Sweet Potato weevil Cylas formicarius (Coleoptera: Brentidae) Cilembu Sweet Potato Plants in Sumedang
Abstrak: Ubi jalar merupakan tanaman pangan strategis sumber karbohidrat peringkat ke-4 setelah padi, jagung dan ubi kayu. Produksi ubi jalar tahun 2016-2020 menurun 34,77%. Kendala yang dihadapi salah satunya adalah serangan hama dan penyakit. Salah satu hama penting pada tanaman ubi jalar adalah hama Cylas formicarius. Penelitian ini bertujuan mendapatkan informasi mengenai tingkat serangan hama boleng pada pertanaman ubi jalar Cilembu di Kabupaten Sumedang. Penelitian dilakukan pada bulan Febuari‒Juni 2022. Pengamatan dilakukan pada 15 lahan petani di tiga desa yang telah ditentukan. Pengamatan struktur umur dan kerapatan populasi C. formicarius di masing-masing lahan petani dilakukan dengan cara mengambil 3 umbi yang menunjukkan gejala terserang berat. Tingkat populasi C. formicarius paling tinggi berada di Desa Cilopang dengan populasi larva 228 ekor, pupa167 ekor, dan imago 199 ekor. Tingkat serangan C. fromicarius paling tinggi mencapai 15.79% di Desa Cilopang., Sweet potato is a strategic food crop and the fourth-largest source of carbohydrates after rice, corn, and cassava. The production of sweet potatoes from 2016 to 2020 has decreased by 34.77%. One of the challenges faced is pest and disease infestation. One significant pest affecting sweet potato plants is the Cylas formicarius weevil. This research aims to gather information on the level of infestation of the sweet potato weevil in Cilembu sweet potato plantations in Sumedang Regency. The study was conducted from February to June 2022. Observations were made on 15 farmer fields in three designated villages. Observations on the age structure and population density of C. formicarius in each farmer's field were conducted by taking three tubers showing severe infestation symptoms. The highest population of C. formicarius was found in Cilopang Village, with a larval population of 228, pupal population of 167, and adult population of 199. The highest infestation rate of C. formicarius reached 15,79% in Cilopang Village.
Keyword: location, planting age, population

Judul: Knowledge, Attitudes, and Actions of Sweet Potato Farmers in the Management of Plant Pest Organisms in Sub-district Cilimus, Kuningan Regency, West Java
Abstrak: Ubi jalar (Ipomoea batatas L.) merupakan salah satu jenis tanaman palawija yang dapat menjadi sumber karbohidrat, sehingga dapat dijadikan sebagai alternatif makanan pokok. Penelitian ini bertujuan mengetahui tingkat pengetahuan, sikap, dan tindakan petani ubi jalar di Kecamatan Cilimus Kabupaten Kuningan dalam upaya pengelolaan Organisme Pengganggu Tanaman (OPT). Penelitian dilakukan dengan menggunakan metode survei langsung di lapangan melalui wawancara dengan petani ubi jalar menggunakan kuesioner terstruktur. Lokasi sampel ditentukan secara terpilih dan penentuan responden dilakukan dengan metode purposive sampling dengan jumlah petani responden sebanyak 60 responden dari empat desa. Hasil penelitian menunjukkan bahwa pestisida masih digunakan dalam mengendalikan OPT. Sebagian besar petani responden telah mengetahui dengan baik praktik budi daya ubi jalar, namun pengetahuan mereka mengenai musuh alami masih terbatas. Mayoritas petani ubi jalar beranggapan bahwa hama boleng dan penyakit layu bakteri merupakan hama penyakit yang sulit dikendalikan. Pengalaman bertani memiliki hubungan yang signifikan dengan sikap petani pada taraf nyata 5% dan 10% dan keikutsertaan dalam program sekolah lapang pengendalian hama terpadu (SLPHT) memiliki hubungan yang signifikan dengan tindakan petani dalam pengelolaan OPT ubi jalar., Sweet potato (Ipomoea batatas L.) is one of secondary crop’s which can be a source of carbohydrates and so that it can be used as an alternative to staple food. The objective of this research was to determine the level of knowledges, attitudes, and actions of sweet potato farmers in Sub-district Cilimus Kuningan Regency in an effort to manage plant pests and diseases. This research was conducted using a direct survey method in the field through interviews with sweet potato farmers using a structured questionnaire. Sampling locations were selected by purposive sampling, while sampling of respondents use a purposive sampling methods with a total of 60 respondents from four villages. The results showed that pesticides were used by the majority of respondents in management of plant pest organisms. Most respondents have known very well the culture practice of sweet potato, but their knowledge about natural enemies are limited. The majority of sweet potato farmers assume that “boleng pest” and bacterial wilt disease are difficult to control. Farming experience has a significant relationship with farmers' attitudes at the 5% and 10% levels. The participation in the integrated pest management field school (SLPHT) program has a significant relationship with farmers' actions in managing plant pest and disease of sweet potato.
Keyword: diseases, farmer, pest, sweet potato

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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