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: Fusarium Wilt Disease of Banana in Binjai, North Sumatera
Abstrak: Tanaman pisang merupakan salah satu komoditas hortikultura penting dan bernilai ekonomi tinggi di Indonesia. Provinsi Sumatera Utara merupakan daerah sentra produksi pisang terbesar kedua di Pulau Sumatera dengan luas lahan mencapai 1 294 ha. Permasalahan organisme pengganggu tanaman (OPT) pada pertanaman pisang telah menyebabkan penurunan luas panen nasional sebesar 2 299 ha dengan total serangan mencapai 70% pada tahun 2018. Salah satu penyakit penting dalam budidaya tanaman pisang adalah penyakit layu fusarium yang sering juga disebut penyakit panama disebabkan oleh Fusarium oxysporum f. sp (Foc). Tujuan penelitian ini adalah menghitung kejadian penyakit layu pada tanaman pisang, mendapatkan informasi pengetahuan petani pisang terhadap penyakit layu, serta mengetahui praktik budidaya yang berkaitan dengan kejadian penyakit di lapang. Penelitian dilakukan di 5 kecamatan yaitu Kecamatan Binjai Utara, Binjai Timur, Binjai Selatan, Binjai Kota, dan Binjai Barat. Metode dilakukan dengan mewawancarai petani, menghitung kejadian penyakit, serta mengamati gejala tanaman terinfeksi. Hasil penelitian ini menunjukkan penyakit layu fusarium pada tanaman pisang telah tersebar hampir di seluruh kecamatan di Kota Binjai. Umur tanaman, varietas, pemupukan organik dan kondisi gulma pada pertanaman pisang berkaitan dengan kejadian penyakit layu fusarium di Kota Binjai. Sebanyak 70% petani tidak mengetahui secara pasti penyebab penyakit layu fusarium pada tanaman pisang., Banana is one of important and high economic value of horticutural product of Indonesia. North Sumatera is the second largest banana producing area in Sumatera reaching 1 294 ha. Pest and disease cause a decrease of the national production area of 2 299 ha with total attacks reaching 70%. One of the important diseases in banana cultivation is fusarium wilt which known as panama diseases, caused by Fusarium oxysporum f. sp. cubense. This research aimed to assess the incidence of fusarium wilt disease, farmers knowledge, and examine the agronomic practices that relate to the incidence of fusarium wilt disease in the field. The research was done in Binjai Utara, Binjai Timur, Binjai Selatan, Binjai Kota, and Binjai Barat district. The methods of this research consisted of farmers interview, field observation, and observation of symptom the infected plants. The result of this research indicate that fusarium wilt disease of banana has spread throughout the distric of Binjai. The age of plant, varieties of banana, aplication of organic fertilization, and weed density related to the incidence of fusarium wilt disease in Binjai. Around 70% of interviewed farmers did not know the casual agent of fusarium wilt disease of banana in Binjai.
Keyword: Fusarium oxysporum f. sp. cubense, Gejala, Kejadian, Varietas

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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