Leaf blight disease caused by pathogenic fungus Phytophthora infestans is the major disease in potato that can reduce its production up to 100%. The use of biological agent Trichoderma viride as an inducing potato resistance against leaf blight disease has been considered potential method. The purpose of this study was to evaluate the use of biological agent Trichoderma viride in inducing potato plant resistance. The parameters observed were the growth of the potato plant and leaf blight intensity. Experimental research with complete randomized design with 6 treatments was applied. The results showed that the application of Trichoderma viride could reduce the intensity of leaf blight disease and increase the growth of the potato plant. Trichoderma viride application could improve the systemic resistance of potato plants.

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Late blight disease caused by Phytophthora infestans, is probably the single most important disease of potatoes worldwide. Infected plants were quickly killed and were difficult for replanting, causing significant losses for the growers. Various control methods were examined including the use of biocontrol agents of Trichoderma spp. The biocontrol potential of Trichoderma viride against potato late blight pathogen, Phytophthora infestans, were studied under greenhouse conditions. The research objective was to determine the ability of biocontrol agents Trichoderma viride to delay late blight disease incidence on potato plants in the field. The in vivo experiment was carried out at potato land area located at BALITSA in Cikole Sub District, Lembang District and Bandung Regency. Completely Randomized Design was used with six treatment and five replicates. The treatment tested consist of control (without pathogen fungal and antagonists fungus application too), control (with pathogen fungal application and without antagonist fungal application), chemical fungicide application, antagonist fungal application 2 weeks before planting, application 1 week after planting and both application 2 weeks before and 1 week after planting. Result of the research showed that application of antagonists fungal could delay disease intensity until 14 days. These antagonist could be used as biological agents initials to control leaf blight disease.Key words: Biological control, Potato late blight, Phytophthora infestans, Trichoderma viride AbstrakPenyakit hawar daun oleh patogen Phytophthora infestans merupakan penyakit utama pada tanaman kentang yang dapat menurunkan produksi hingga 100%, sehingga mengakibatkan kerugian yang nyata bagi para petani kentang. Penggunaan agensia hayati Trichoderma viride sebagai penginduksi ketahanan tanaman kentang terhadap penyakit hawar daun merupakan metode yang sangat potensial dilakukan. Tujuan penelitian ini adalah mengevaluasi penggunaan agensia hayati Trichoderma viride dalam menginduksi ketahanan tanaman kentang terhadap penundaan penyakit hawar daun pada penelitian di lapangan/ rumah kasa. Metode penelitian menggunakan penelitian eksperimental dengan pola penelitian rancangan acak lengkap dengan 6 perlakuan. Hasil penelitian menunjukkan bahwa aplikasi Trichoderma viride dapat menunda kemunculan penyakit hawar daun dibandingkan dengan kontrol dan fungisida. Aplikasi Trichoderma viride menunda penyakit hawar daun sampai 14 hari.

Probiotics from lactic acid bacteria (LAB) are widely used in the livestock industry to replace the use of Antibiotics Growth Promoters (AGPs). LAB is a culture starter that is widely used in fermented foods. LAB has the ability to adapt to different substrates, resulting in its wide use in the fermentation of various food products. MRS (De Man Rogosa Sharpe) medium is a growth medium for LAB, but for the industrial-scale requires a high cost, therefore innovation is needed to find alternative culture media using local raw material. Tofu Liquid Waste (TLW) can be used as a growth medium for probiotic bacteria because it still contains enough nutrients source for growth. This study aims to determine the formulation and optimization of culture media for LAB isolates using tofu liquid waste. Six Lab isolates from chickens gastrointestinal tract were used in experiments to determine the ability to grow on TLW culture media. The growth assays are conducted by inoculating LAB isolates in the culture media formulation that divided into 4 groups, consisting of medium A (TLW+molasses 1,5%+skim milk 5%), B (TLW+molasses 1,5%+skim milk 2,5%), C (TLW+molasses 3%+skim milk 5%), and D (TLW+molasses 3%+skim milk 2,5%). The best LAB isolate to grow on TLW medium was Lactobacillus paracasei. The best TLW modification medium for Lactobacillus paracasei growth is D media. Modified media consisting of TLW, molasses and skim milk can be used as an alternative medium for LAB growth.

Lack of nutrients is the major cause of potato production to decrease and potato plant not to grow well. The objective of the study was to analyze the effect of Plant Growth Promoting Rhizobacteria (PGPR) on the growth and the production of potato. The research was conducted in Kledung Village, Temanggung Regency (1,136 meter above the sea level), in 04 March – 04 June 2018. Randomized Block Design (RBD) with five treatments was applied with five treatments each of which was placed in a different plot and each plot was filled with 40 plant treatments. On the first plot, no treatment was given (P1); the second plot was given chemical fertilizer (P2), the third plot was supplemented with PGPR one dose (P3), the fourth plot was PGPR two dose (P4), and the last was the fifth plot treated with GA hormone (P5). The results showed that there was no significant difference in plant height. The highest potato production was in the group treated with PGPR 1 time was 277.1 g and the lowest was in the P2 group, which was 101.4 gr. PGPR directly increases the availability of nutrients for plants, and increases fertility. So, it, can be concluded that the administration of PGPR one dose is the best dose and increases potato production.