ABSTRAKColletotrichum spp. sebagai penyebab penyakit antraknosa merupakan salah satu faktor pembatas produksi pepaya (Carica papaya). Tujuan penelitian ini ialah mengidentifikasi spesies Colletotrichum spp. dari berbagai bagian tanaman pepaya yang menunjukkan gejala antraknosa. Sebanyak 20 galur Colletotrichum spp. berhasil diisolasi, selanjutnya dilakukan pengelompokkan menjadi 3 tipe morfologi berdasarkan kemiripan koloni dan bentuk konidia. Sebanyak 12 galur dari kelompok I dan 3 galur dari kelompok II diidentifikasi sebagai C. gloeosporioides sensu lato berdasarkan morfologi koloni dan bentuk konidia silinder yang kedua ujungnya membulat. Sementara itu 1 galur dari kelompok II secara molekuler diidentifikasi sebagai C. magnum. Empat galur dari kelompok III dengan bentuk konidia melengkung dan berujung runcing, serta membentuk setae pada medium buatan diidentifikasi secara molekuler sebagai C. truncatum. C. gloeosporioides ditemukan pada batang, tangkai daun, dan buah. C. magnum dan C. truncatum masing-masing ditemukan pada tangkai daun dan buah. Selain karakter morfologi dan molekuler, perbedaan respons pertumbuhan koloni terhadap suhu dapat digunakan untuk mengonfirmasi spesies Colletotrichum tersebut. Keberadaan Colletotrichum yang menginfeksi pada bagian batang dan tangkai daun pepaya di pertanaman dan temuan spesies C. magnum dan C. truncatum pada tanaman ini merupakan laporan pertama di Indonesia.Kata kunci: C. gloeosporioides, C. magnum, C. truncatum, morfologi, molekuler ABSTRACT Colletotrichum spp. is known as the causal agent of anthracnose and considered as an important limiting factors on papaya production. The objective of this study was to determine the species of Colletotrichum spp. from various plant parts of papaya (Carica papaya) showing anthracnose symptom. Twenty isolates of Colletotrichum spp. was isolated and were grouped into 3 morphological groups based on colony similarity, conidial morphology, and setae formation. A total of 12 isolates of group I and 3 isolates of group II were identified morphologically as C. gloeosporioides sensu lato based on cylindrical conidia with rounded on both ends and colony morphology. Meanwhile, 1 isolate of group II was molecularly identified as C. magnum. Four isolates of group III with a curved and pointedend conidia, and produced setae on artificial medium were identified molecularly as C. truncatum. C. gloeosporioides was obtained on stem, leaf petiole, and fruit. C. magnum and C. truncatum were only obtained on leaf petiole and fruit, respectively. In addition to morphological and molecular characters, differences in colony growth responses to temperature can be used to distinguish the species of Colletotrichum. To our knowledge the existence of anthracnose symptom on the stems and leaf petioles of papaya in the fields and the discovery of C. magnum and C. truncatum isolated from papaya was the first report in Indonesia.

Ability of watermelon endophytic bacteria to suppress development of leaf spot disease caused by Colletotrichum sp.  A studi on assay of endophytic bacteria to control Colletotrichum sp., causal agent of leaf spot disease on watermelon, was conducted. Colletotrichum sp. was isolated from infected leaf of leaf spot disease, while endophytic bacteria were isolated from stem, leaf, and root of watermelon healthy plant. Antagonistic assay was conducted by dual culture method. Hyphal abnormalities as a result of antagonistic assay was observed using light microscope. To determine the ability of endophytic bacterial isolates to control leaf spot disease, watermelon seeds were treated by dipping the seed in endophytic bacterial suspension. Seven endophytic bacterial isolates showed to inhibit Colletotrichum sp. to some extent. Two isolates DS 01 and BS 01 showed relatively high inhibition zone compared to others, therefore were choosen for further study. Abnormal hyphae such as broken, lysis, twisted, curled, and swollen hyphae were recorded as the result of antagonistic assay. Watermelon seed treatment revealed that dipping the seed in endophytic bacterial suspension of DS 01 and BS 01 reduced leaf spot disease to 12 and 24%, but inhibited seed growth by 12% and 44%, respectively. It seemed that all treatments showed to reduce seedling performance i.e seedling height, leaf number, and dry weight, compared to that of (-) control. DS 01 however seemed to increase dry weight of watermelon plants.

Penelitian ini bertujuan untuk mengisolasi bakteri dari tanaman karuk pada bagian rhizosfer, filosfer, filoflane serta bakteri endofit yang berada di dalam tanaman karuk. Menguji patogenesitas bakteri yang diperoleh dan menguji kemampuan bakteri calon agens hayati dalam memacu pertumbuhan tanaman dan kemampuannya menghambat pertumbuhan cendawan patogen Fusarium oxysporum secara invitro. Penelitian dilakukan pada Bulan September 2015 sampai dengan Januari 2016 di Laboratorium Nematologi Tumbuhan Departemen Proteksi Tanaman, Institut Pertanian Bogor. Hasil isolasi bakteri calon agens hayati dari tanaman karuk menunjukan bahwa diperoleh 73 isolat bakteri yang terdiri dari bakteri yang berasal dari Rizosfer sebanyak 12, endofit sebanyak 19, Rizoplan sebanyak 20 bakteri, filoplan sebanyak 18 bakteri dan 4 isolat konsorsium. Hasil uji hemolisis pada media agar darah terdapat 58 bakteri yang positif dan tidak digunakan pada pengujian selanjutnya. Hasil uji hipersensitif pada tembakau terdapat 7 isolat bakteri yang lolos dan dilanjutkan ke pengujian berikutnya. Hasil uji pertumbuhan pada benih padi bakteri isolat FP8  memiliki nilai tinggi tanaman terbaik sebesar 13.48 cm dan pada panjang akar terbaik pada perlakuan FP 16. Pengujian dual kultur  perlakuan F8, F12, F16, RP13, RP14 mampu membuat pertumbuhan hifa cendawan Fusarium oxysporum menjadi abnormal jika dibandingkan dengan kontrolnya