Judul: Integrated pest management practices by organic coffee growers In Regency of Jayawijaya
Abstrak: Research was conducted in Regency of Jayawijaya-Papua from January until March 2011, with the objectives to obtain information on pest management practices by organic coffee growers. Number of farmers interviewed were 42 in District of Walesi and 46 in District of Kurulu. Coffee growers in the District Walesi and Kurulu generally have received training and guidance on coffee cultivation, management of pests and diseases, processing, standardization, and marketing. The cumulative mean percentage of farmers participation in training was 37-39%. The most important pests attacking coffee in Jayawijaya was berry borer, Hypothenemus hampei Fer (Coleoptera: Scolytidae). In District of Kurulu 100% of respondents applied fungus Beauveria bassiana to control the coffee berry borer, while in District Walesi only 53%. In addition, 30% of respondents in Kurulu also install broca trap to control the berry borer, while in Walesi only 7%. Other control techniques practiced by famers include clearing of weeds, pruning, and application of compost and manure. About 71% of respondents in Kurulu have heard about organic certification, while in Walesi only 29%. According to 40% of respondents in Kurulu organic coffee was associated with free of pesticides, whereas 50% of respondents in Walesi associated organic coffee with free of chemical fertilizers. Coffee farmers in Jayawijaya nearly 65.22% were already familiar with certification of organic coffee.
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Judul: Identification of Pests and Diseases along with Their Control in  the Gayo Coffee (Coffea arabica) Agroforestry System in Central Aceh
Abstrak: Sistem agroforestri adalah sistem pengelolaan lahan yang mempertimbangkan aspek sosial, ekonomi dan ekologi. Kopi Gayo (Coffea arabica) merupakan komoditi utama masyarakat Desa Mude Nosar, Aceh Tengah dengan sistem yang digunakan adalah sistem agroforestri. Disisi lain, serangan hama dan penyakit k opi Gayo menyebabkan penurunan produktivitas dan penelitian terkait identifikasi hama serta penyakit pada sistem agroforestri kopi Gayo masih sangat terbatas. Tujuan penelitian ini adalah i) menganalisis komposisi, struktur, dan keanekaragaman vegetasi, ii) mengidentifikasi jenis hama dan penyakit pada Kopi Gayo dan penaungnya, iii) menghitung intensitas serangan hama dan penyakit pada sistem agroforestri k opi Gayo, serta iv) mengidentifikasi potensi pengendalian hama dan penyakit terpadu pada sistem agroforestri kopi Gayo di Desa Mude Nosar. Metode yang digunakan adalah purposive sampling dan analisis vegetasi serta menghitung serangan hama dan penyakit. Gejala serangan diidentifikasi di Laboratorium Patologi Hutan dengan melihat struktur makroskopis dan mikroskopis cendawan. Hasil penelitian menunjukkan bahwa rumput kerbau (Paspalum conjugatum) dan kopi Gayo secara berturut-turut mendominasi tingkat tumbuhan bawah dan pancang. Lamtoro (Leucaena leucocephala) mendominasi tingkat semai, tiang dan pohon. Keanekaragaman jenis (H’) tingkat semai dan tumbuhan bawah termasuk sedang dan tingkat pancang, tiang, dan pohon termasuk rendah. Struktur tegakan membentuk kurva J terbalik. Hama yang ditemukan adalah kutu loncat (Heteropsylla cubana) dan ulat jengkal (Hyposidra talaca). Penyakit yang ditemukan yaitu antraknosa dan karat daun. Intensitas serangan hama kutu loncat, penyakit antraknosa dan karat daun masing-masing dibawah 30%. Pengendalian hama dan penyakit pada sistem agroforestri kopi Gayo secara terpadu dengan pengelolaan agroforestri secara organik dengan pemanfaatan limbah kulit kopi dan kotoran ternak, serta dengan pemanfatan musuh alami. Musuh alami yang berpotensi yaitu Trichoderma harzianum, semut rangrang (Oecophylla smaragdina), dan laba-laba (Araneae)., Agroforestry is a land management system which considers social, economic and ecological aspects. Gayo coffee (Coffea arabica) is the main commodity which planted by local community of Desa Mude Nosar, Central Aceh using agroforestry system. On the other hand, Gayo coffee pests and diseases reduce the productivity and only a few studies have been undertaken to identify pests and diseases in Gayo coffee with agroforestry system. The study aimed to i) analyze the composition, structure, and diversity of vegetation, ii) to identify the types of pests and diseases in Gayo Coffee and its shade, iii) to calculate the intensity of pest and disease attacks on Gayo coffee in agroforestry system, and iv) to identify the potential of integrated pest control and disease in the Gayo coffee with agroforestry system in Desa Mude Nosar. The method used in this study was purposive sampling and vegetation analysis along with calculating pest and disease attacks. Symptoms of the attack were identified at Forest Pathology Laboratory by looking at the macroscopic and microscopic structures of the fungus. The results showed that rumput k erbau (Paspalum conjugatum) and Gayo coffee dominated the understorey and sapling levels. Lamtoro (Leucaena leucocephala) dominates the seedling, pole and tree stake. Species diversity (H') of seedlings and understorey levels was moderate and the level of saplings, poles, and trees was low. The stand structure forms an inverted J curve. The pests found were fleas (Heteropsylla cubana) and black looper (Hyposidra talaca).
Keyword: Agroforestry, Gayo coffee, Lamtoro, Agroforestry, Gayo coffe, Lamtoro

Judul: Invers Drazin dari Matriks Toeplitz Singular
Abstrak: Matriks Toeplitz adalah matriks yang setiap unsur pada diagonal utama bernilai sama dan setiap unsur pada subdiagonal yang bersesuaian dengan diagonal utama juga bernilai sama. Matriks singular adalah matriks yang tidak bisa ditentukan inversnya. Akan tetapi, dapat diupayakan untuk ditentukan inversnya menggunakan invers matriks yang diperumum. Invers Drazin merupakan salah satu jenis invers matriks yang diperumum. Pada karya ilmiah ini ditentukan invers Drazin dari matriks Toeplitz singular dengan menggunakan metode Leverrier Faddeev. Kemudian, ditentukan invers Drazin dari matriks Toeplitz singular yang direpresentasikan sebagai penjumlahan segitiga bawah dan segitiga atas matriks Toeplitz berdasar pada teorema Gohberg dan Semencul., Toeplitz matrix is a matrix in with element on the main diagonal has the same value and on the subdiagonal corresponding to the main diagonal also has the same value. Singular matrix is a matrix that has no inverse. However, it can be attempted to determine the inverse using a generalized inverse matrix. Inverse Drazin is a type of generalized matrix inverse. This paper discussed the inverse Drazin for a singular Toeplitz matrix using the Leverrier Faddeev method. Then, the Drazin inverse of the singular Toeplitz matrix which is represented as a sum of products of lower and upper triangular Toeplitz matrix based on Gohberg and Semencul theorem.
Keyword: inverse Drazine, singular Toeplitz matrix