Effect of Plant Oils and Extracts on Uredospores of Hemileia vastatrix Germination and Attack Intensity

Abstract
Description
Rust disease caused by fungus Hemileia vastatrix is a major disease of Arabica coffee, which reduces yield by 20%–70%. Botanical fungicide is a potential alternative because environmentally friendly and safe to humans health. The research aimed to analyze the effect of oils and extracts of fungicidal plants on uredospore germination and attack intensity of H. vastatrix. The research was conducted in laboratory and greenhouse of Indonesian Industrial and Beverages Crops Research Institute (IIBCRI), Sukabumi, from January to December 2016. The plant oils were of cloves, citronella, Reutealis trisperma, and neem, while the plant extracts used were mahogany, Ageratum conyzoides, and wood vinegar. Those oils and extracts were assessed on uredospores germination of H. vastatrix, both in vitro and on coffee seedlings in the greenhouse. A complete randomized block design was used with 9 treatments and 5 replications. The oils and extracts at 5% concentration were applied on coffee leaves of 6 months old plants then inoculated with H. vastratrix uredospora simultaneously. Attack symptoms, incubation period, attack percentage and intensity were observed. The results showed that plant oils and extracts used in present study effectively reduced the uredospora germination of H. vastatrix. However, oils of neem and R. trisperma as well as A. conizoides extract are more potential to suppress H. vastatrix infection in coffee leaves in greenhouse and reduced attack intensity from 22.2% to 3.6%; 5.2%; and 7.6% with inhibitory level at 83.8%; 76.6%; and 65.8%, respectively. Therefore, they are considered as potential biocontrols for rust disease.
Penyakit karat daun yang disebabkan oleh Hemileia vastatrix  merupakan penyakit utama pada kopi Arabika. Serangan patogen ini dapat menurunkan produksi 20%–70%. Fungisida nabati memberi peluang yang lebih baik untuk pengendalian penyakit karat daun karena bersifat ramah lingkungan dan aman bagi kesehatan. Tujuan penelitian adalah menganalisis pengaruh minyak dan ekstrak tanaman terhadap perkecambahan uredospora dan intensitas serangan H. vastatrix. Kegiatan dilakukan di laboratorium dan rumah kaca Balai Penelitian Tanaman Industri dan Penyegar (Balittri), Sukabumi, mulai Januari sampai Desember 2016. Minyak tanaman yang digunakan adalah minyak cengkeh, serai wangi, kemiri sunan, dan nimba, sedangkan ekstrak tanaman yang digunakan adalah mahoni, babadotan, dan asap cair. Minyak dan ekstrak tanaman diuji terhadap perkecambahan uredospora H. vastatrix secara in vitro dan pada benih  kopi di rumah kaca. Penelitian menggunakan rancangan acak lengkap dengan 9 perlakuan dan 5 ulangan. Benih kopi berumur 6 bulan diperlakukan dengan minyak dan ekstrak tanaman dengan konsentrasi 0,5%. Pada saat bersamaan, tanaman diinokulasi uredospora H. vastatrix. Pengamatan dilakukan terhadap gejala serangan, masa inkubasi, serta persentase dan intensitas serangan. Hasil penelitian menunjukkan bahwa minyak tanaman (cengkeh, nimba, serai wangi, dan kemiri sunan) dan ekstrak tanaman (babadotan, mahoni, dan asap cair) dapat menekan perkecambahan uredospora H. vastatrix. Minyak nimba dan kemiri sunan serta ekstrak babadotan lebih potensial menekan infeksi H. vastatrix pada daun kopi di rumah kaca dengan penurunan intensitas serangan dari 22,2% menjadi 3,6%; 5,2%; dan 7,6%  serta dengan daya hambat sebesar 83,8%; 76,6%; dan 65,8%. Minyak nimba dan kemiri sunan serta  ekstrak babadotan potensial digunakan untuk mengendalikan karat daun kopi.
Keywords
H. vastatrix; plant extract; plant oil; rust leaf disease, , Ekstrak tanaman, H. vastatrix; minyak tanaman; penyakit karat daun kopi,
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