Judul: Beberapa pendekatan dalam mengatasi penyakit bengkak akar pada kubis
Abstrak: Penelitian dilakukan di laboratorium Fitopatologi IPB Bogor dan rumah plastik di IPB Begor serta di Kebun Percobaan Pasir Sarongge. Penelitian dilakukan untuk menguji beberapa pendekatan dalam mengatasi penyakit bengkak akar yang mencakup: pengujian resistensi, pemanfaatan residu tanaman yang berasal dari pertanaman sebelumnya, dan modifikasi pH tanah yang berasal dari Pacet dan Lembang dengan penambahan kapur. Bahan inokulum diambil dari tanaman kubis yang terserang penyakit bengkak akar sebanyak 10 gram, ditumbuk dengan mortar, lalu diblender selama satu menit dengan di­ tambah air suling steril 10 ml, kemudian disaring, dan di­ peroleh suspensi inokulum. Konsentrasi inokulum ditentukan dengan menghitung jumlah spora/ml cairan dengan haemasito-meter. Residu tanaman yang dipakai berupa daun-daun dari sisa tanaman sehabis panen. Daun-daun tersebut dijemur dalam panas matahari selama dua hari, setelah itu dimasukkan ke dalam oven dengan suhu 6o⁰c selama 24 jam. Bahan yang sudah kering digiling dengan gilingan daging, lalu disaring dengan ayakan berukuran 2x2 mm. Untuk perlakuan residu tanaman digunakan residu tanaman: tanah ialah 1 : 100 atau 1% (b/b kering}.
Keyword: Resintenci;, Patogen;, Inokulum;, Bogor Agricultural University;

Judul: Pengamatan Penyakit Pada Pertanaman Kubis (Brassica oleracea L. var. capitata) di Kebun Percobaan Balai Penelitian Hortikulura Lembang dan Sekitarnya
Abstrak: Tujuan praktek lapang ini adalah untuk mengamati jenis penyakit pada pertanaman kubis melalui pengamatan gejala se- rangannya dan penentuan intensitas serta luas serangannya. Metode yang digunakan adalah wawancara dan pengamatan di lapang. Wawancara dilakukan dengan pihak penanggung ja- wab Kebun Percobaan dan petani yang bersangkutan sedang pengamatan di lapang dilakukan dengan metode penarikan naman contoh yang didasarkan pada sistem diagonal. ta- Hasil pengamatan menunjukkan bahwa jenis-jenis penya- kit yang terdapat pada pertanaman kubis di KP BPH dan rak- yat adalah: penyakit akar gada (Plasmodiophora brassicae Wor.), penyakit busuk hitam (Xanthomonas campestris (Pam.) Down), penyakit downy mildew (Peronospora parasitica (Fr.) Full. Persoon Fries), penyakit bercak daun (Alternaria sp.) dan penyakit bercak daun (Mycosphaerella sp.). Umumnya in- tensitas dan luas serangan penyakit-penyakit tersebut lebih tinggi pada pertanaman kubis rakyat dibandingkan dengan per- tanaman kubis KP ΒΡΗ. Luas serangan P. brassicae baik di pertanaman kubis KP BPH maupun rakyat adalah tinggi, rata-rata di atas 40 persen. Cendawan tersebut mengakibatkan pertanaman kubis gagal untuk dipanen....
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Judul: Thermal Characteristics and Dynamics of Tropical Cyclone over Western North Pacific Ocean: A Case Study of Typhoon Songda (Chedeng) 2011
Abstrak: The frequent occasion of Tropical Cyclone (TC) over Western North Pacific (WNP) Ocean lies from 10˚N to 26˚N and 121˚E to 170˚E. Sources of TC development come from warm ocean temperature where latent heat is released during condensation processes and subsequently concentrated in the boundary layer. Relative humidity at 850-700 hPa is responsible to produce the most intense storm. Meanwhile, weak vertical wind shear between 850-200 hPa is one of the dynamical factors that lead to the development of TC. Pressure level of 850-200 hPa is chosen to minimize the thermodynamic effect in the lower troposphere. Typhoon Songda (Chedeng in the Philippines) or TSC lasted from May 18th to 30th, 2011 and strengthened into powerful Super Typhoon stage between May 24th and 27th. Long curving track and the exhibition of all sequences of TC life cycle, TSC is then considered as an ideal case of TC. The objective of the study with case of TSC is to investigate the role of thermal characteristics and dynamics on TC intensity. The research is carried out by using Advanced Research of Weather Research and Forecasting model (WRF ARW model) version 3.3. Two domains are employed in the model. The first domain situate from 02˚N to 40˚N and 118˚E to 149˚E and cover spatial resolution () of 33.1 km. The second domain situate from 09˚N to 27˚N and 119˚E to 132˚E with of 11 km. Timestep of the model () is 120 seconds. The model is supported by the following physical parameterization, i.e., Yonsei University Scheme (YSU) in the boundary layer, Kain-Fritsch scheme (KF) in the cumulus, and WRF Single-Moment 3-class scheme in the microphysics. Initial meteorological condition prior to the formation of the cyclone is generated using WRF ARW standard-release model. Sensitivity of the model output is obtained from a selected single-parameter change scenarios, namely, 10 % to 20 % decrease and increase of wind shear initial data at 850-200 hPa, and by 10 % to 20 % decrease of relative humidity initial data at 850-700 hPa. The result showed that the negative correlations between wind shear and intensity are found in wind shear scenarios. Wind shears of 10 ms-1 which lead to strengthening of the wind intensity in the early period of Typhoon development are found in wind shear scenarios. The effect of wind shear changes on wind intensity is statistically significant in the 20 % wind shear scenarios. During mature stage, weak wind intensity occurred when wind shear increase as given in the WRF standard-release and the 20 % decreasing scenario. Different situation is found in the 20 % increasing scenario where wind shear tend to weak and lead to strong wind intensity at this stage. Meanwhile, the reduction of moisture supply at 850-700 hPa resulting from 20 % decreasing relative humidity play a major role in the weakening of wind intensity and reduces mechanical energy of the cycle process as much as 300 J kg-1.
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