11 ISSN: 0215-7950 *Alamat penulis korespondensi: Departemen Proteksi Tanaman, Fakultas Pertanian, Institut Pertanian Bogor, Jalan Kamper, Kampus IPB Dramaga 16680. Tel: 0251-8629362, Surel: andikasepti@apps.ipb.ac.id Volume 19, Nomor 1, Januari 2023 Halaman 11–18 DOI: 10.14692/jf.19.1.11–18 Keefektifan Galur PGPR dalam Pengendalian Penyakit Karat Putih dan Peningkatan Pertumbuhan Tanaman Krisan Efectiveness of Various PGPR Lineage in Controlling White Rust Diseases and Growth Promotion of Chrysanthemum Suryo Wiyono, Andika Septiana Suryaningsih*, Astika Widhi Pratiwi Institut Pertanian Bogor, Bogor 16680 ABSTRAK Karat putih merupakan salah satu penyakit penting pada tanaman krisan di Indonesia. Teknologi yang efektif untuk pengendalian penyakit ini di Indonesia tidak tersedia. Penelitian ini bertujuan menguji potensi lima galur (Pseudomonas diminuta P14, Bacillus frmus J8, Lysinibacillus fusiformis C71, AKBR, AKS) plant growth promoting rhizobacteria (PGPR) untuk pengendalian penyakit karat putih yang disebabkan Puccinia horiana pada tanaman krisan di lapangan. Formulasi komersial Pseudomonas fuorescens dan Bacillus polymyxa dipilih sebagai pembanding. Percobaan dilakukan di lapangan dengan mengaplikasikan suspensi rizobakteri pada tanaman krisan. Semua galur PGPR yang diuji mampu menekan insidensi dan keparahan penyakit karat putih. PGPR galur Bacillus frmus J8 paling efektif menekan karat putih, sedangkan galur Lysinibacillus fusiformis C71 paling efektif meningkatkan pertumbuhan tanaman krisan. Kelima galur rizobakteri dan formulasi komersial meningkatkan diameter bunga. Kata kunci: diameter batang, diameter bunga, pengendalian hayati, Puccinia horiana. ABSTRACT White rust disease caused by Puccinia horiana is the most destructive disease of Chrysanthemum in Indonesia. There was no available efective control measure against the disease in Indonesia. This research aimed to examine the potency of fve strains of plant growth-promoting rhizobacteria (PGPR) for controlling white rust disease on Chrysanthemum under feld conditions. Five PGPR strains (Pseudomonas diminuta P14, Bacillus frmus J8, Lysinibacillus fusiformis C71, AKBR, AKS) and one commercially formulated PGPR were used in this study. The research was carried out in farmer felds with a randomized complete block experimental design. PGPR was applied by plant watering using bacterial suspension. All PGPR strains were efective in suppressing the white rust disease incidence and its severity. The most efective PGPR strain to suppress white rust disease was Bacillus frmus J8 and the most efective strain to increase the growth of Chrysanthemum plants was Lysinibacillus fusiformis C71. The fve PGPR strains tested and commercial formulation increased the diameter of the fower. Keyword: biological control, fower diameter, Pucciana horiana, stem diameter.