Judul: Fungus Pathogenicity Test and Identification that cause Root Rot on Ketapang Kencana (Terminalia mantaly) Plants
Abstrak: Serangan penyakit busuk akar banyak menyerang berbagai jenis tanaman kehutanan, seperti sengon, akasia, agathis, dan pinus. Serangan busuk akar juga ditemukan pada pohon ketapang kencana yang menyebabkan rubuhnya pohon dan merugikan manusia yang berada di sekitarnya. Penelitian ini bertujuan melakukan uji patogenisitas dan identifikasi jenis cendawan penyebab penyakit busuk akar pada tanaman ketapang kencana. Metode penelitian meliputi kegiatan uji patogenisitas dengan menginokulasikan isolat cendawan dan identifikasi jenis menggunakan ciri morfologi cendawan. Cendawan yang berhasil diidentifikasi adalah Fusarium sp. dan Botryodiplodia sp.. Botryodiplodia sp. teridentifikasi sebagai cendawan patogen yang diduga menyebabkan gejala busuk akar dan pangkal batang pada tanaman ketapang kencana karena menimbulkan serangan pada contoh uji berupa kayu sengon. Isolat Botryodiplodia sp. memiliki karakteristik makroskopis koloni berwarna putih yang kemudian berubah abu-abu, dengan tekstur menyerupai kapas, dan memiliki karakteristik mikroskopis konidiofor verticillate, konidia oval dengan dua ujung meruncing, hifa bersekat hialin yang kemudian berubah gelap.
Keyword: Botryodiplodia sp., Fusarium sp., Combretaceae, decay, morphology

Judul: Fungus Pathogenicity Test and Identification that causes Leaf Disease on Sengon in Dramaga Bogor Permanent Nursery
Abstrak: Sengon (Paraserianthes falcataria (L.) Nielsen) merupakan jenis pohon cepat tumbuh (fast-growing species) dan mudah didapat karena sudah banyak dibudidayakan di Indonesia. Usaha perbanyakan sengon melalui kegiatan pembibitan di persemaian banyak menemui kendala penyakit. Penelitian ini bertujuan mengidentifikasi cendawan penyebab penyakit daun pada tanaman sengon, serta menghitung luas dan intensitas serangan cendawan penyebab penyakit daun pada sengon di Persemaian Permanen Dramaga Bogor. Metode penelitian ini adalah rangkaian uji patogenisitas meliputi pengamatan lapang, postulat Koch, dan identifikasi jenis cendawan. Penelitian menggunakan Rancangan Acak Lengkap Faktorial (RALF). Gejala penyakit yang ditemukan pada daun sengon umur sekitar dua bulan yang ada di lokasi pengamatan adalah penyakit gugur daun, bercak daun, dan hawar daun. Hasil identifikasi cendawan penyebab gugur daun adalah Rhizoctonia sp., cendawan penyebab bercak daun adalah Colletotrichum sp., dan cendawan penyebab hawar daun adalah Fusarium sp.. Fusarium sp. menghasilkan persentase serangan tertinggi dengan luas serangan sebesar 67,34% dan intensitas serangan sebesar 57,28%., Sengon (Paraserianthes falcataria (L.) Nielsen) is a fast-growing tree species and easy to obtain because it has been widely cultivated in Indonesia. Sengon plant propagation is carried out through nursery activities in nurseries. The study aimed to identify the fungus that causes leaf disease on sengon plants and calculate the extent and intensity of attacks by the fungus that causes leaf disease on sengon in the Dramaga Bogor Permanent Nursery. This research method carried out pathogenicity test activities, including field observations, Koch's postulates, and the identification of fungal species. The study used a Completely Randomized Factorial Design (RALF). The disease symptoms found on around two months of sengon leaves old at the observation site were leaf fall, leaf spot, and leaf blight. The results of identifying the fungus that causes leaf fall were Rhizoctonia sp.. This fungus that causes leaf spots is Colletotrichum sp., and the fungus that causes leaf blight is Fusarium sp.. Fusarium sp. resulted in the highest percentage of attacks, with a disease incidence of 67,34% and disease severity of 57,28%.
Keyword: characteristics, identification, Koch's postulates, morphology

Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
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