Judul: Penyakit Pada Tanaman Krisan (Chrysanthemum morifolium) di PT Natalia Nursery Bogor
Abstrak: Krisan merupakan tanaman hias yang banyak diminati karena keindahannya. Penurunan produksi bunga krisan di Indonesia, khususnya di Jawa Barat, disebabkan oleh beberapa faktor termasuk patogen. Penelitian ini bertujuan untuk mendapatkan informasi mengenai intensitas penyakit dan mengidentifikasi patogen yang menginfeksi tanaman krisan di PT Natalia Nursery Bogor. Pengamatan meliputi jenis gejala, insidensi penyakit dan tingkat keparahan, serta hasil produksi. Pengamatan dilakukan setiap minggu selama lima kali pada tiga petak tanaman yang berbeda. Identifikasi patogen penyebab dilakukan dengan pengamatan mikroskopis dan dikonfirmasi dengan studi literatur. Berdasarkan hasil penelitian, ada lima penyakit yang ditemukan yaitu karat putih (Puccinia horiana), layu fusarium (Fusarium oxysporum), bercak daun (Septoria sp.), diduga virus/viroid dan nematoda puru akar (Meloidogyne spp.). Secara umum, insidensi dan keparahan penyakit mengalami peningkatan setiap minggunya. P. horiana adalah patogen dominan yang menginfeksi tanaman krisan dengan tingkat keparahan penyakit hingga 40,81% pada varietas rentan. Varietas krisan yang paling tahan terhadap infeksi patogen adalah Puspita Nusantara. Terdapat adanya korelasi antara insidensi dan keparahan penyakit karat putih dengan hasil produksi bunga krisan., Chrysanthemum is a highly demanded ornamental plant due to its beauty. The reduction of chrysanthemum production in Indonesia, especially in West Java, might be caused by several factors including pathogen infections. The field investigation aimed to obtain the disease intensity and to identify the pathogen infecting chrysanthemum plants at PT Natalia Nursery Bogor. The type of symptoms, disease incidence and severity, as well as yield were measured. The observations were conducted every week for five times at three different plots. Identification of the causal pathogens were carried out by microscopic observation and confirmed by literature studies. Five diseases were found, namely white rust (Puccinia horiana), fusarium wilt (Fusarium oxysporum), leaf spot (Septoria sp.), suspected virus/viroid, and root-knot nematode (Meloidogyne spp.). The disease incidence and severity was increasing every week. The P. horiana was the dominant pathogen infecting chrysanthemum in the nursery with disease severity up to 40,81%. The most susceptible chrysanthemum variety against pathogen infection was Puspita Nusantara. The disease incidence and severity white rust can affect the yield of chrysanthemum flowers.
Keyword: chrysanthemum, pest, incidence, severity

Judul: Mealybugs (Hemiptera: Pseudococcidae) on Chrysanthemum And Their Management Efforts at PT. Natalia Nursery, Bogor West Java
Abstrak: Krisan merupakan tanaman hias bunga potong dan menjadi komoditas ekspor utama florikultura di Indonesia. Usaha dalam budidaya tidak terlepas dari organisme penganggu tanaman, salah satunya kutu putih. Penelitian ini bertujuan mengidentifikasi spesies kutu putih pada krisan, menentukan intensitas serangan dan mengamati gejala kerusakan Phenacoccus solenopsis pada krisan serta upaya pengendaliannya. Identifikasi dilakukan dengan mengoleksi kutu putih yang ada pada tanaman krisan kemudian dibuat preparat mikroskop. Pengamatan intensitas serangan dilakukan pada tiga petak krisan, dan gejala kerusakan dilakukan dengan menginfestasi Ph. solenopsis. Upaya pengendalian dilakukan dengan menguji keefektifan minyak mimba (Azadirachta indica) terhadap Ph. solenopsis, yaitu dengan aplikasi minyak mimba tunggal, sabun sebelum mimba, campuran sabun dan mimba serta kontrol. Metode pengujiannya yaitu larutan disemprot pada tanaman yang diinfestasi kutu putih. Kematian Ph. solenopsis diamati 24, 48, 72, 96 JSP. Hasil identifikasi terdapat empat spesies kutu putih, yaitu: Ferrisia virgata, Ph. solenopsis, Pseudococcus jackbeardsleyi, dan Planacoccus minor yang menjadi hama pada krisan. Spesies F. virgata dan Pl. minor merupakan catatan baru pada tanaman krisan. Intensitas serangan Ph. solenopsis tertinggi yaitu 8.72% dengan populasi 73.5 kutu putih per petak. Kerusakan Ph. solenopsis pada fase vegetatif menyebabkan malformasi di bagian pucuk daun sehingga ukurannya menyusut, keriting, penebalan daun, pembengkokan batang serta pengurangan ukuran secara keseluruhan. Gejala fase generatif menyebabkan daun pelindung seperti terpelintir, bakal bunga tidak berkembang dan pembengkokan tangkai bunga. Aplikasi sabun dilanjut dengan mimba menunjukkan paling efektif terhadap Ph. solenopsis dengan mortalitas sebesar 100% pada 96 JSP., Chrysanthemum is the most exported ornamental cut flower in Indonesia. Its cultivation cannot be separated from pests attacks, especially mealybugs. This study aims to identify mealybugs species on chrysanthemum, to determine the intensity attack level, damage symptom of Phenacoccus solenopsis and its control efforts. Mealybug identification was made by collecting mealybugs and preparing on slide. The intensity and population development of mealybugs were observed on three plots. The damage symptoms caused by mealybugs, a certain number of Ph. solenopsis were infested to the plants and observed. Control efforts were carried out by testing the effectiveness of Neem (Azadirachta indica) against Ph. solenopsis, the plant was treated with single neem oil, combined with soap, applied after soap and control. The method is a solution sprayed on chrysantemum that mealybugs invest in. The death Ph. solenopsis was observed at 24, 48, 72, 96 HAT. The identification result shows that there are four mealybugs species, i.e: Ferrisia virgata, Ph. solenopsis, Planacoccus minor, and Pseudococcus jackbeardsleyi as pest on chrysanthemum. The species of F. virgata and Pl. minor are new mealybugs pests record to chrysanthemum. The highest intensity of Ph. solenopsis is recorded as many as 8.72 % or 73.5 mealybugs per plots. Damage due to mealybugs in the vegetative phase causes malformation in the shoots leaves reported as reduction of leaf size, wavy leaves, curled, thickened, twisted leaves, incurvation of stem, and reduction of overall plant size. Further damage on generative phase showed the incurvation of bud and flower stalk. The most effective treatment against Ph. solenopsis with a mortality of 100% at 96 hour after treatment on soap spraying continued by neem.
Keyword: Azadirachta indica, identification, Malformation, Pseudococcus jackbeardsleyi

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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