Judul: Identification of Diseases in Three Varieties of Local Banana Plants (Musa spp.) in Lumajang Regency, East Java
Abstrak: Kabupaten Lumajang merupakan sentra produksi pisang di Jawa Timur, memiliki 33 jenis sehingga menjadi pusat keanekaragaman kultivar pisang. Produksi pisang berfluktuasi diakibatkan oleh beberapa faktor, salah satunya penyakit. Penelitian ini bertujuan mengetahui penyakit penting pada tiga jenis tanaman pisang lokal yaitu Mas Kirana, Agung Semeru, dan Pasak Kresek Madjang, serta mendapatkan informasi tingkat insidensi / kejadian penyakitnya. Penelitian ini dilakukan menggunakan metode survei dengan pengamatan langsung di Kecamatan Gucialit, Pasrujambe, Ranuyoso, Randuagung, dan Senduro. Sampel terdiri atas daun, batang, akar dan tanah yang diambil pada tanaman bergejala penyakit (purposif sampling). Pengamatan kejadian dan keparahan penyakit dilakukan dua minggu sekali. Cendawan pada sampel daun dan batang bergejala dilembabkan lalu diamati atau ditumbuhkan pada media PDA (Potato Dextrose Agar). Nematoda diekstraksi dari sampel tanah dengan metode flotasi-sentrifugasi, sedangkan sampel akar menggunakan mist chamber. Petani menggunakan pola tanam monokultur dan tumpangsari, serta melakukan pengelolaan seperti sanitasi lahan dan pemangkasan daun tua. Penyakit tanaman pisang yang berhasil diidentifikasi adalah bercak daun Cordana (Neocordana musae), sigatoka kuning (Mycospherellla musicola), dan layu Fusarium (Fusarium oxysporum f.sp cubense). Fitonematoda yang ditemukan adalah genus Criconemoides, Helicotylenchus, Meloidogyne, Pratylenchus, Radopholus, Rotylenchulus, Rotylenchus, dan Tylenchus.. Kata kunci : Fusarium, konidia, morfologi, Pratylenchus, sigatoka kuning
Keyword: morfologi, fusarium, konidia, Pratylenchus, Sigatoka kuning

Judul: Incidence and Severity of Leaf Spot Disease on Banana Plants (Musa spp.) at the IPB Experimental Garden Sukamantri, Bogor, West Java
Abstrak: Banana (Musa spp.) is one of the horticultural commodities that consumed by many people in Indonesia. Pests and diseases affects the quality of banana production. This study aims to identify the cause of leaf spot disease in banana plants and determine the incidence and severity of the disease. This research was conducted at the IPB experimental field station, in Sukamantri Village, Tamansari District, Bogor Regency, West Java. Observations of disease progression were conducted from September to October 2022 for five consecutive weeks. Identification of the cause of the disease is done by taking samples of symptomatic banana leaves, then further identified in the laboratory. Disease incidence and severity data were tabulated using Microsoft Office Excel 2013 and analyzed descriptively. Two types of leaf spot disease were identified, i.e. cordana and sigatoka leaf spot. Cordana leaf spot only infects Raja Bulu variety while sigatoka leaf spot infects Raja Bulu, Mas Kirana, and Ambon Kuning varieties. The incidence of cordana leaf spot disease caused by Cordana musae reaches 100% with an average disease severity of 30.66-67.70%. The incidence of sigatoka leaf spot caused by Mycosphaerella musicola in Raja Bulu variety was 62.96-66.67%, while in Mas Kirana and Ambon Kuning varieties reached 100% with the average severity of disease in Raja Bulu variety ranging from 9.62-17.33%, in Mas Kirana variety 31.38-62.00%, and in Ambon variety 33.17-67.05%.
Keyword: bercak cordana, bercak daun sigatoka, Cordana musae, identifikasi, Mycosphaerella musicola

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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