Articles

Found 39 Documents
Search

Waduk Parangjoho dan Songputri: Alternatif Sumber Erupsi Formasi Semilir di daerah Eromoko, Kabupaten Wonogiri, Jawa Tengah Bronto, Sutikno; Mulyaningsih, Sri; Hartono, G.; Astuti, B.
Indonesian Journal on Geoscience Vol 4, No 2 (2009)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1126.755 KB) | DOI: 10.17014/ijog.v4i2.71

Abstract

http://dx.doi.org/10.17014/ijog.vol4no2.20091The Semilir Formation was typically originated from products of a very explosive volcanic activity, i.e. breccias, lapillistones, and tuffs containing abundant pumice. It has a light grey to white colour and high silica andesite to dacite in composition, mainly rich in volcanic glass and quartz. Sedimentary structures of these volcanic rocks are massive, grading, planar bedding, and cross-bedding to antidunes, with grain size varies from ash (≤ 2 mm) to lapilli (2 – 64 mm) to bomb and block (> 64 mm). The formation is widely distributed from the west side (Pleret and Piyungan areas, Bantul Regency, Special Province of Yogyakarta) until Eromoko area in the east (Wonogiri Regency, Jawa Tengah Province). Stratigraphically, the Semilir Formation underlies the Nglanggeran Formation, and overlies the Mandalika Formation in the eastern part and Kebo-Butak Formation in the western part. Geomorphological- and lithological analyses of the Semilir Formation in areas of Parangjoho and Song- putri Dams, Eromoko Sub-regency, Wonogiri Regency indicate that the two depressions were alternatively volcanic sources of the Semilir Formation in the Eromoko area. This is proved by the presence of co-ignimbrite breccias(co-ignimbrite lag fall deposits), that descriptively they are polymict breccias. This rock is characterized by a mixing of pumice and various hard rock fragments that primarily are juvenile materials (volcanic blocks, bombs), accessory-, and accidental rock fragments set in pumice-rich volcanic ash and lapilli sizes. The accessory materials came from older volcanic rocks, whereas the accidental ones were originated from basement rocks. During a caldera forming event or a destruction period of an older composite volcanic cone(s), all older rocks resting above the magma chamber were ejected to the surface by a very high magmatic pressure. Since they were heavier than the juvenile material, most accessory and accidental rock fragments were left (lag fall) in caldera rim behind the ash and pumice flow. In the dam areas of Parangjoho and Songputri, the lag fall fragments consisting of andesite, pyroxene andesite, dacite, and pumice, being 10 – 150 cm in diameter are set in pumice-rich lapilli tuffs. Some of the rock fragments are volcanic blocks and bombs, while the older rocks are angular to very angular shape, having prismatic jointing or jigsaw-crack structures. The eruptions in the Parangjoho and Songputri craters were controlled by north-south trending fractures, and they resemble to the Katmaian caldera explosion type.  
Gunung Api purba Watuadeg: Sumber erupsi dan posisi stratigrafi Bronto, Sutikno; MulyaningSih, Sri; Hartono, G.; Astuti, B.
Indonesian Journal on Geoscience Vol 3, No 3 (2008)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (856.976 KB) | DOI: 10.17014/ijog.v3i3.53

Abstract

http://dx.doi.org/10.17014/ijog.vol3no3.20081Pillow lava flows of pyroxene basalt containing 50 wt.% SiO are exposed at Opak River, west of Watuadeg Village, Sleman - Yogyakarta. The length of flow structures is between 2 – 10 m, with diameter of 0.5 – 1.0 m and it has a glassy skin at the surface body. Flow directions vary from N70E in the northern side, through N 120E in the middle to N 150E in the southern side. About 150 m away from the river to the west, there is a small hill about 15 m high, that has a similar composition with the pillow lavas. Both lava flows and the small hill are composed of pyroxene basalt, dark grey in color, hypocrystalline vitrophyre to porphyritic texture, with fine-grained phenocrysts of pyroxene (10 %) and plagioclase (25 %) set in glassy groundmass. These data indicate that the small hill was the eruption source of the basaltic pillow lavas. The lavas are overlain by pumice-rich volcaniclastic rocks, composed of tuff, lapillistones and pumice breccias, that are known as the Semilir Formation. Near the contact with lavas, the volcaniclastic rocks contain some fragments of pyroxene basalt, similar composition with the pillow lavas. This fact, together with analyses of petrology, volcanology, and radiometric dating show that the basaltic pillow lavas are unconformably overlain by the Semilir Formation.  
Dinamika pengendapan lahar permukaan pada alur-alur lembah di bagian selatan Gunung Api Merapi, Yogyakarta Mulyaningsih, Sri; Sampurno, Sampurno; Zaim, Yahdi; Puradimaja, Deny Juanda; Bronto, Sutikno
Indonesian Journal on Geoscience Vol 1, No 3 (2006)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (907.621 KB) | DOI: 10.17014/ijog.v1i3.15

Abstract

http://dx.doi.org/10.17014/ijog.vol1no3.20062Endapan aliran rombakan Gunung Api Merapi, yang lebih dikenal sebagai lahar, terbentuk dari hasil longsoran endapan awan panas yang dipicu oleh curah hujan yang sangat tinggi. Pada saat ini, endapan awan panas tersebut berasal dari guguran kubah lava. Material suspensi tersebut selanjutnya menuruni lereng dengan kecepatan yang tinggi, menghasilkan aliran turbulen. Aliran tersebut biasanya berkembang pada daerah dengan perbedaan morfologi berkemiringan lereng tinggi ke landai, atau yang sering dikenal sebagai daerah tekuk lereng. Studi ini didasarkan pada pengamatan dan pengukuran fragmen lahar yang berukuran besar di permukaan. Analisis meliputi arah penyirapan, bentuk, dan besar butir fragmen. Hasil penelitian mendapatkan model arah aliran fragmen besar lahar dari bagian atas aliran rombakan, yang membentuk “model punggung katak” atau “model punggung gajah”. Bagian depan katak atau gajah (kepala) yaitu arah aliran atau bagian depan aliran. Hasil penelitian juga menunjukkan bahwa model tersebut berlaku pada fragmen dengan diameter 90 cm atau lebih besar. Di daerah penelitian, fragmen dengan diameter 90 cm mencapai jarak hingga 22 km dari sumbernya. Hasil penelitian ini dapat digunakan sebagai model untuk menentukan arah aliran lahar (aliran rombakan) purba yang sumbernya belum diketahui.  
Perkembangan Geologi pada Kuarter Awal sampai Masa Sejarah di Dataran Yogyakarta Mulyaningsih, Sri; Sampurno, Sampurno; Zaim, Yahdi; Puradimaja, Deny Juanda; Bronto, Sutikno; Siregar, Darwin Alijasa
Indonesian Journal on Geoscience Vol 1, No 2 (2006)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1562.85 KB) | DOI: 10.17014/ijog.v1i2.13

Abstract

http://dx.doi.org/10.17014/ijog.vol1no2.20065The uplift of Southern Mountains in Early Pleistocene has formed the Yogyakarta Basin. In this basin, the Merapi volcanic activity has been developing. Based on 14C dating in cinder deposits exposed at Cepogo, the volcanic activity took place since ±42 ka. While on the basis of K/Ar dating in andesitic lava at Bibi Volcano, the activity took place since 0.67 ma. The high in the south and the appearance of Merapi volcanic dome in the north had caused a fl at valley. The southern part of the valley is bounded by the Southern Mountains and the western part is bounded by the West Progo Mountains. In the present time, the lithology of the areas which are interpreted as a palaeo-valley is composed of black clay deposits. This black clay is a contact between the basement rocks and Merapi volcanic deposits. The black clay deposits exposed in the Progo River (Kasihan) has been developed since ±16.59 to 0.47 ka, while in the Opak River (Watuadeg) 6210 y BP. Younger black clay deposits intersecting with lahars are also exposed at the Winongo River and have an age of 310 y BP. The age data of volcanic stratigraphy shows that Merapi activities had taken place since ±6210 up to ±310 years ago.  
Pengaruh Cekaman Air Terhadap Karakter Fisiologis Tembakau Temanggung dan Kaitannya dengan Hasil dan Kadar Nikotin Rajangan Kering Djumali, .; Mulyaningsih, Sri
Buletin Tanaman Tembakau, Serat & Minyak Industri Vol 5, No 2 (2013): Oktober 2013
Publisher : Balai Penelitian Tanaman Pemanis dan Serat (Balittas)

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

Tembakau temanggung ditanam pada akhir musim penghujan sehingga sering mengalami cekaman air dan berakibat pada penurunan hasil dan kadar nikotin rajangan kering. Penelitian bertujuan untuk mengetahui pengaruh cekaman air terhadap karakter fisiologis tembakau temanggung serta kaitannya dengan hasil dan kadar nikotin rajangan kering. Penelitian dilakukan di rumah kaca Balittas Malang pada Maret–Oktober 2010 dengan menggunakan Rancangan Petak Terbagi dan diulang 3 kali. Petak utama terdiri atas 3 jenis tanah yakni Komplek Eutrudepts-Hapludalfs, Komplek Dystrudepts-Hapludalfs, dan Vitraquands. Anak petak terdiri atas 5 tingkat kelembapan tanah (60, 70, 80, 90, dan 100% dari kapasitas lapangan). Hasil penelitian me-nunjukkan bahwa cekaman air pada tiga jenis tanah berpengaruh negatif terhadap konduktivitas stomata, laju fotosintesis, hasil dan kadar nikotin rajangan kering, serta berpengaruh positif terhadap bobot spesifik daun. Pengaruh cekaman air terhadap hasil rajangan kering terjadi melalui penurunan konduktivitas stomata dan laju fotosintesis selama fase setelah pemangkasan. Pengaruh cekaman air terhadap kadar nikotin terjadi me-lalui penurunan konduktivitas stomata sebelum pembungaan dan setelah pemangkasan, penurunan laju fotosintesis setelah pemangkasan, dan peningkatan bobot spesifik daun setelah pemangkasan. Temanggung tobacco is grown at the end of wet season which so often experience water stress. Water stress can decrease dry slice yield and nicotine content. The study was aimed to determine the effect of water stress on physiological characteristics of temanggung tobacco and its relation to dry slice yield and nicotine content. Research was conducted in greenhouse of Indonesian Sweetener and Fibre Crops Research Institute, Malang from March to October 2010 using splitplot design and repeated three times. The main plot consisted of three types of soil (Complex Eutrudepts-Hapludalfs, Complex Dystrudepts-Hapludalfs, and Vitraquands). The Subplot consisted of five soil moisture levels (60, 70, 80, 90, and 100% of field capacity). The results showed that water stress on the third series of the soil negatively affect stomatal conductivity, the photosynthesis rate, dry slice yield and nicotine content, as well as the positive effect on specific leaf weight. Effect of water stress on dry slice yield occurred through the decrease of stomata conductivity and photosynthetic rate during the phase after topping. The effect of water stress on nicotine content occurred through a reduction in stomatal conductivity before flowering and after topping, decrease of photosynthetic rate after topping, and increase of specific leaf weight after topping.
Pengaruh Macam Tanaman Sela Terhadap Pertumbuhan Dan Hasil Jarak Pagar (Jatropha curcas L.) Hasil Rehabilitasi Tahun Ketiga Mulyaningsih, Sri; Hariyono, Budi
Buletin Tanaman Tembakau, Serat & Minyak Industri Vol 5, No 2 (2013): Oktober 2013
Publisher : Balai Penelitian Tanaman Pemanis dan Serat (Balittas)

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

Pada pertanaman jarak pagar yang masih muda (umur 1–2 tahun) dengan jarak tanam 2 m x 2 m ada lahan kosong yang tidak termanfaatkan. Upaya optimalisasi pemanfaatan lahan adalah menanam tanaman sela, sehingga petani mempunyai pendapatan dari tanaman sela sebelum jarak pagar menghasilkan. Penelitian ini bertujuan untuk mengetahui pengaruh tanaman sela terhadap pertumbuhan dan hasil jarak pagar dan men-dapatkan macam tanaman sela yang sesuai pada jarak pagar hasil rehabilitasi (penyambungan) pada tahun ketiga. Penelitian dilaksanakan di Kebun Percobaan Muktiharjo, Kabupaten Pati, Jawa Tengah mulai bulan Januari hingga Desember 2011, menggunakan rancangan acak kelompok diulang enam kali. Perlakuan yang diuji adalah: 1) jarak pagar + kacang tanah, 2) jarak pagar + kedelai, 3) jarak pagar + kacang hijau, 4) jarak pagar + wijen, dan 5) jarak pagar tanpa tanaman sela. Ukuran petak 8 m x 8 m, jarak tanam jarak pagar 2 m x 2 m. Jarak tanam tanaman sela kacang tanah, kedelai, dan kacang hijau masing-masing 25 cm x 25 cm, sedangkan jarak tanam wijen 50 cm x 25 cm. Hasil penelitian menunjukkan bahwa hasil biji kering tanaman jarak pagar dengan tanaman sela kedelai, kacang hijau, dan wijen tidak berbeda nyata dengan hasil biji kering jarak pagar monokultur kecuali dengan kacang tanah. Hasil biji kering jarak pagar + kedelai 655,87 kg/ha + 1.316,07 kg/ha; jarak pagar + kacang hijau 644,70 kg/ha + 1.557,5 kg/ha; jarak pagar + wijen 511,49 kg/ha + 1.416,67 kg/ha; jarak pagar + kacang tanah yaitu 358,31 kg/ha + 1.015,28 kg/ha; dan hasil biji kering tanaman jarak pagar tanpa tanaman sela 602,27 kg/ha. Tumpang sari jarak pagar dengan keempat macam tanaman sela (kacang tanah, kedelai, kacang hijau, dan wijen), efisien dalam pemanfaatan lahan dan layak secara ekonomi untuk ditanam dan dikembangkan bersama dengan tanaman jarak pagar rehabilitasi tahun ketiga dengan nilai NKL masing-masing: 1,32; 1,64; 1,98; 1,72 dan B/C ratio 4,79; 1,88; 5,71; 7,03. In young jatropha plantation (1–2 years aged) with 2 m x 2 m spacing there is fallow land. The effort to optimize of land use was by planting intercrops, so that the farmers get income before the jatropha plant produce. This study aimed to determine the effect of intercrops on growth and yield of jatropha and get suitable intercrops in the jatropha rehabilitated plantation (by grafting) in the third year. Research was conducted at Muktiharjo Research Station, Pati, Central Java from January to December 2011. The experiment was arranged in randomized block design with 6 replications. Treatments were 1) intercropping physic nut + peanut, 2) intercropping physic nut + soybean, 3) intercropping physic nut + mungbean, 4) intercropping physic nut + sesame, and 5) physic nut monoculture. Plot size was 8 m x 8 m, plant distance of physic nut were 2 m x 2 m, and plant distances for peanut, soybean, and mungbean were 25 cm x 25 cm and for sesame was 50 cm x 25 cm. Result showed that intercropping was not significantly effect on seed yield of physic nut, however intercropping physic nut with peanut decreased the physic nut seed yield. Seed yield of intercropping physic nut + soybean 655.87 kg/ha + 1,316.07 kg/ha; physic nut + mungbean 644.70 kg/ha + 1,557.55 kg/ha; physic nut + sesame 511.49 kg/ha + 1,416.67 kg/ha; physic nut + peanut 358.31 kg/ha + 1,015.28 kg/ha; and physic nut monoculture 602.27 kg/ha. Intercropping physic nut with four kinds of intercrop plant (peanut, soybean, mungbean, and sesame), efficient land use and economically viable for the grown and developed along with physic nut rehabilitation third year with the value of each land equi-valent ratio (LER) 1.32; 1.64; 1.98; 1.72 intercropping and B/C ratio 4.79; 1.88; 5.71; and 7.03.
Gunung api maar di Semenanjung Muria Bronto, Sutikno; Mulyaningsih, Sri
Indonesian Journal on Geoscience Vol 2, No 1 (2007)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (874.556 KB) | DOI: 10.17014/ijog.v2i1.27

Abstract

http://dx.doi.org/10.17014/ijog.vol2no1.20074Three maars are well identifi ed in the Muria Peninsula, i.e. Bambang Maar, Gunungrowo Maar, and Gembong Maar. The maars were formed by monogenetic volcanic eruptions due to the interaction between heat source (magma), groundwater and calcareous basement rocks. This interaction is able to produce very high pressure of gas and steam causing phreatic explosions, followed by phreatomagmatic- or even magmatic explosions and ended by a lava extrusion. Satellite image analyses have recognized twelve circular features, comprising Bambang Maar, Gunungrowo Maar, and Gembaong Maar. Phisiographically, these maars are characterized by circular depressions which are surrounded by hills that are gently sloping down away from the crater or having a radier pattern morphology. Outcrops and drilling core in the circular areas that are considered as volcanic maars are lava fl ows, pyroclastic breccias, lapillistones, and tuffs, located far away from the eruption centres of Muria and Genuk Volcanoes. One of the circular features, i.e. Jepara Circular Feature, is also supported by negative anomaly (<30 mgal) showing a circular pattern. In the future, a maar volcano could possibly erupt depending on the tectonic reactivity in the region.  
Vulkanisme kompleks Gunung Patiayam di Kecamatan Jekulo, Kabupaten Kudus, Provinsi Jawa Tengah Mulyaningsih, Sri; Bronto, Sutikno; Kusnaedi, Ari; Simon, I.; Prasetyanto, I. W.
Indonesian Journal on Geoscience Vol 3, No 2 (2008)
Publisher : Geological Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1010.037 KB) | DOI: 10.17014/ijog.v3i2.49

Abstract

http://dx.doi.org/10.17014/ijog.vol3no2.20082The Mount Patiayam Complex was interpreted by previous researchers as “Patiayam Dome”. That was reasoned by dips following its slope directions. Field data record that lithology of the complex of Mount Patiayam is dominated by volcanic rocks. The summit of the complex is composed of igneous rocks of pyroxene basalt rich in leucite minerals, associated with autoclastic breccia and beds of volcanic breccia rich in pyroxene basalt and pumice, pumiceous breccia, and tuff. Its flanks are composed of epiclastic rocks of lahar and fluvial deposits. Some river valleys, such as Pontang River, locally consist of pyroclastic breccia, autoclastic breccia and pumiceous breccia, that are overlain by marly limestone and black clay of swampy deposits. Based on the rock composition, the volcanism had more dominated geological processes compared with sedimentary. Mineral composition of volcanic deposits of the Mount Patiayam is closer to Mount Lasem volcanic rocks than Mount Muria, i.e. absarockites, shoshonites and trachyandesite. But, based on the long distance between Patiayam and Lasem, about 60 km, those volcanic rocks could not be produced by Mount Lasem. The Patiayam volcanic deposits were produced by its own volcanic activities. Therefore, the complex of Mount Patiayam is a paleo-volcano. The interpretation is also supported by the landsat imagery, showing depression-shapes in a caldera ring-like. There are four caldera features called as Rim 1,Rim 2,Rim 3, and Rim 4, which crosses each others.  
PENGARUH SINTERING TERHADAP SIFAT MAGNETIK BAHAN KOMPOSIT Co-AlxOy Mulyaningsih, Sri; Purwanto, Setyo; Adi, Wisnu Ari; Manaf, Azwar
Jurnal Sains Materi Indonesia EDISI KHUSUS: OKTOBER 2007
Publisher : Center for Science & Technology of Advanced Materials - National Nuclear Energy Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1201.555 KB) | DOI: 10.17146/jusami.2007.0.0.5118

Abstract

PENGARUH SINTERING TERHADAP SIFAT MAGNETIK BAHAN KOMPOSIT Co-AlxOy. Penelitian dilakukan dengan menghaluskan campuran serbuk kobal (Co) dan aluminium (Al)menggunakan High Energy Milling (HEM) dengan perbandingan Co73Al27 wt%, kemudian dipres dan dilanjutkan dengan proses sintering.Waktu milling divariasikan antara 4,5 jam, 12 jam dan 20 jam sedangkan proses sintering pada suhu 384 ºC dan 484 ºC. Setelah proses sinter ditemukan beberapa puncak-puncak baru yang diidentifikasi sebagai Co-Al2O4. Hasil pengukuran VSM menunjukkan proses milling dan sinter mengakibatkan nilai saturasi Ms menurun pada semua sampel. Sedang nilai koersivitas Hc untuk sampel hasil milling nilai tertinggi 367 Oe dicapai pada sampel 4,5 jammilling, sedang untuk 12 jam dan 20 jam adalah 275 Oe dan 317 Oe. Untuk sampel yang disinter nilai koersivitas cenderung naik yaitu pada sampel 12 jam milling dan sinter 384 ºC dan 484 ºC adalah 275 Oe, 285 Oe dan 305 Oe, dan untuk 20 jam milling 317 Oe, 345 Oe dan 345 Oe.
PATOGENISITAS DUA ISOLAT LOKAL JAMUR Nomuraea rileyi (FARLOW) SAMSON TERHADAP Helicoverpa armigera HUBNER (LEPIDOPTERA: NOCTUIDAE) INDRAYANI, IGAA.; PRABOWO, HERI; MULYANINGSIH, SRI
853-8212
Publisher : Pusat Penelitian dan Pengembangan Perkebunan

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

ABSTRAKEpizootik Nomuraea rileyi telah berkembang secara alami dalampopulasi lebih dari 30 spesies serangga inang, termasuk H. armigera.Penelitian ini dilakukan di Laboratorium Patologi Serangga BalaiPenelitian Tanaman Pemanis dan Serat Malang mulai Januari hinggaDesember 2011, tujuannya untuk mengetahui patogenisitas dua isolat lokaljamur entomopatogen N. rileyi terhadap larva H. armigera. Penelitianterdiri atas dua faktor perlakuan, faktor 1 adalah dua isolat lokal N. rileyi,yaitu ML 01 dan LG 02, dan faktor 2 adalah konsentrasi konidia, yaitu: 2,2x 10 5 ; 4,5 x 10 5 ; 2,2 x 10 6 ; 4,5 x 10 6 ; 2,2 x 10 7 ; 4,5 x 10 7 ; 2,2 x 10 8 ; 4,5 x10 8 konidia/ml, dan kontrol. Setiap perlakuan disusun dalam RancanganAcak Kelompok Faktorial dengan tiga kali ulangan. Aplikasi jamur padalarva H. armigera dilakukan dengan metode kontaminasi permukaanmedia yang berupa daun kapas muda (1cm 2 ) di dalam ruangan bersuhu25±1⁰C dan kelembapan 75-80%. Parameter yang diamati adalahmortalitas larva, LC 50 dan LT 50 , serta bobot larva. Hasil penelitianmenunjukkan bahwa tingkat patogenisitas isolat ML 01 terhadap larva H.armigera lebih tinggi dibandingkan dengan isolat LG 02. Isolat ML 01menyebabkan mortalitas larva H. armigera antara 51,13-85,56% (LC 50  =2,5 x 10 2  Konidia/ml) dan isolat LG 02 antara 43,36-78,90%, (LC 50  =5x10 6  Konidia/ml). LT 50 isolat ML 01 antara 5,2-5,5 hari, sedangkan isolatLG 02 antara 6,8-7,0 hari, terutama pada konsentrasi 2,2-4,5 x 10 8konidia/ml. Terdapat korelasi positif yang erat antara konsentrasi konidiadan mortalitas larva baik pada isolat ML 01 (r=0,975) maupun LG 02(r=0,980), demikian pula antara konsentrasi konidia dan kehilangan bobotlarva pada isolat ML 01 (r=0,982) dan LG 02 (r=0,972).Kata kunci: Helicoverpa armigera, Nomuraea rileyi, patogenisitas, isolat,mortalitasABSTRACTThe epizootic of the fungi Nomuraea rileyi has naturally developedin more than 30 species of insect host population, including cottonbollworm, H. armigera. A study on pathogenicity of two local isolates ofNomuraea rileyi (Farlow) Samson fungi against Helicoverpa armigera(Hubner) (Lepidoptera: Noctuidae) was conducted at Insect PathologyLaboratory of Indonesian Sweeteners and Fibers Crops Research Institute(ISFCRI) in Malang from January to December 2011 in order to find outthe pathogenicity of the isolates against H. armigera larvae. This studyconsists of two factors as treatment. The first factor was N. rileyi isolates,e.g. ML 01 and LG 02, and the second factor were eight conidiaconcentrations, viz. 2.2 x 10 5 ; 4.5 x 10 5 ; 2.2 x 10 6 ; 4.5 x 10 6 ; 2.2 x 10 7 ; 4.5x 10 7 ; 2.2 x 10 8 ; 4.5 x 10 8 conidia/ml, and one untreated control.Treatments were arranged in Factorial Randomized Block Design withthree replications. Suspense of conidia was applied by surfacecontamination method of cotton leaf as medium at 25±1⁰C of temperatureand 75-80% of humidity. Parameter observed were larval mortality, LC 50 ,LT 50 , and larval weight. Result showed that ML 01 isolate was morepathogenic against H. armigera larvae than LG 02 isolate based on larvalmortality, LC 50 , and LT 50 . Percentage of mortality of H. armigera larvaedue to ML 01 and LG 02 infection were 51.1- 85.56% and 43.36-78.90%,respectively. The LC 50 of ML 01 and LG 02 isolates was 5.2-5.5 days and6.8-7.0 days, respectively.There are closest positive correlation betweenconidia concentration and percentage of mortality on ML 01 (r = 0.975)and LG 02 (r = 0.980) isolates as well as between conidia concentrationand larval weight loss on ML 01 (r = 0.982) and LG 02 (r = 0.972)isolates.Key words: Helicoverpa armigera, Nomuraea rileyi, pathogenicity,isolate, mortality