The aim of this research was to examine in vitro and in vivo anti fungal activity of citronella leaves extract against Colletotrichum sp caused antrachnose disease on chilli. The in vitro and in vivo research used randomized completely design (RCD) with one factor and five level. The factor was citronella leaves extract and the level were 0,1 % (v/v), 0,2 % (v/v), 0,3 % (v/v), 0,4 % (v/v), 0,5 % (v/v). Negative control treatment was conducted by growing Colletotrichum sp on PDA (in vitro) and chili (in vivo) without citronella leaves extract while positive control was conducted by growing Colletotrichum sp on PDA (in vitro) and chili (in vivo) containing synthetic fungicide. The in vitro study showed that the higher concentration of citronella leaves extract caused higher growth inhibition of Colletotrichum sp. Whereas the in vivo study resulted that higher concentration of citronella leaves extract caused lower incubation period of Colletotrichum sp, intensity of disease and weight loss of chillies. The highest concentration of citronella leaves extract (0,5%) has higher antifungal activity compared to other treatments and negative control while lower than positive control.

Tujuan penelitian ini untuk mengetahui potensi Pseudomonas sp. asal rhizosper padi sebagai agen hayati untuk mengendalikan penyakit hawar daun bakteri (Xanthomonas oryzae pv. oryzae) secara in vitro. Penelitian dilaksanakan di Laboratorium Agroekoteknologi, Fakultas Pertanian, Universitas Sultan Ageng Tirtayasa pada bulan Juni-September 2014. Penelitian  menggunakan rancangan acak lengkap non faktorial dengan lima ulangan. Perlakuan terdiri dari 6 isolat Pseudomonas sp. (Ps 6, Ps 29, Ps 39, Ps 40, Ps 45, dan Ps 46) yang memiliki kemampuan antagonis dan 1 kontrol air (tanpa bakteri) sebagai pembanding, sehingga terdapat 35 satuan percobaan. Isolat-isolat bakteri Pseudomonas sp. yang diuji daya hambatnya secara analisis tidak memiliki pengaruh, baik antar isolat maupun terhadap kontrol (tanpa bakteri perlakuan). Namun, secara keseluruhan mempengaruhi yaitu dengan terbentuknya zona bening menunjukkan adanya tingkat pengendalian. Isolat-isolat bakteri Pseudomonas sp. memiliki kemampuan yang relatif sama dalam mengendalikan bakteri Xanthomonas oryzae pv. oryzae. Meski demikian, isolat Ps 39 dan memiliki zona bening yang cenderung lebih tinggi.

The purpose of this research was to determine the antagonistic bacteria Pseudomonas spp. of paddy roots endophytic against disease blast (Pycularia oryzae) in vitro. This research was conducted at the Laboratory of Agroecology, Faculty of Agriculture, University of Sultan Ageng Tirtayasa on April to June 2015. This research implemented experimental one factor that arranged in Completely Randomized Design with three replications. The treatment consisted of 9 isolates of Pseudomonas sp. which was screened from endophytic roots of paddy plants.  The test  results  showed  that  antagonistic in  vitro  testing could inhibit the growth P. oryzae. Inhibition of 9 isolates to the growth Pseudomonas spp. had the significant clear zone. Isolate Ps 17 (58.89%), Ps 22 (54.44%), Ps 37 (52.06%) and Ps 39 (61.42%) have the largest inhibition. The results showed that the bacteria Pseudomonas sp. on this research is potential on controlling disease blast in paddy plant.