Keefektifan Minyak Cengkeh, Serai Wangi, dan Ekstrak Bawang Putih terhadap Penyakit Vascular Streak Dieback (Ceratobasidium theobromae) Pada Kakao - Rita Harni; Baharuddin Baharuddin (Pusat Penelitian dan Pengembangan Perkebunan, 2014)
Ceratobasidium theobromae merupakan patogen penyebab penyakit vascular streak dieback (VSD) pada tanaman kakao, dapat menurunkan produksi bahkan kematian tanaman. Penyakit ini sulit dikendalikan karena berada dalam jaringan pembuluh. Penelitian bertujuan menguji keefektifan minyak cengkeh dan serai wangi serta ekstrak bawang putih terhadap C. theobromae penyebab penyakit VSD. Penelitian telah dilakukan pada perkebunan kakao rakyat hasil sambung samping berumur 2 tahun yang terserang penyakit VSD di Desa Andomesinggo, Kecamatan Besulutu, Kabupaten Konawe, Sulawesi Tenggara dari bulan April sampai Desember 2013. Rancangan yang digunakan adalah acak kelompok (RAK) 6 perlakuan dengan 6 ulangan, masing-masing perlakuan diamati 15 tanaman. Perlakuannya adalah minyak cengkeh, serai wangi, cengkeh + serai wangi, ekstrak bawang putih, fungisida kimia ditiokarbamat (sebagai pembanding) dan kontrol (tanpa perlakuan). Ekstrak dan minyak diaplikasikan setiap bulan dengan konsentrasi 5 ml/l, dengan cara menyemprotkan suspensi ke seluruh bagian tanaman (250 ml/pohon). Pengamatan gejala serangan, perkembangan penyakit, persentase dan intensitas serangan dilakukan setiap bulan, sedangkan tingkat keefektifan fungisida nabati dihitung pada akhir pengamatan. Hasil penelitian memperlihatkan minyak cengkeh, serai wangi, dan bawang putih dapat menurunkan persentase dan intensitas serangan penyakit VSD pada tanaman kakao. Persentase penurunan intensitas serangan terbesar dan nyata diperoleh pada perlakuan minyak cengkeh dan serai wangi, masing-masing 38,6% dan 31,6% dan keduanya potensial digunakan sebagai fungisida nabati untuk mengendalikan penyakit VSD.Kata kunci: Kakao, VSD, minyak cengkeh, minyak serai wangi, ekstrak bawang putihVascular streak dieback disease caused by Ceratobasidium theobromae is a major disease that causes yield loss and even kill a mature cocoa tree. This disease is difficult to control due to located inside the vascular tissue. The objective of this research was to study the antifungal activity of clove oil, citronella oil and garlic extract against C. theobromae causing VSD disease. The research was carried out at cocoa plantations which derived from side grafting and attacked by VSD disease in Andomesinggo Village, Besulutu District, Konawe Regency, Southeast Sulawesi, from April to December 2013. The design used in this study was a randomized block design with 6 treatments and 6 replications, each treatment consisted of 15 plants. The treatments used were clove oil, citronella, clove + citronella, garlic extract, chemical fungicide (as a comparison) and control (without treatment). The extracts and oil applied every month at a concentration of 5 ml/l, by spraying the suspension onto all parts of the plant (250 ml/tree). Observation of attack symptoms, progression of the disease, the percentage and intensity of the attacks were carried out every month, whereas the level of effectiveness of botanical fungicides is calculated at the end of experiment. The results showed that clove oil, citronella and garlic extract can reduce the percentage and intensity of VSD disease attacks on cocoa plant. The highest percentage of the reduction of disease intensity were obtained in the use of clove oil and citronella at about 38.6% and 31.6% respectively, and both of them are potential to be used as botanical fungicide to control VSD disease.