Identifikasi dan Karakterisasi Penyakit Bintik Batang dan buah pada Tanaman Buah Naga (Hylocereus spp.) di Indonesia I

[Identification and Characterization of Stem and Fruit Canker Diseases on Dragon Fruit (Hylocereus spp.) in Indonesia]Kendala utama budidaya tanaman buah naga di Indonesia adalah masalah penyakit. Ada beberapa jenis patogen yang menyerang tanaman buah naga, namun penyakit yang paling berbahaya dan sangat merugikan adalah penyakit bintik batang. Penelitian ini bertujuan mengkarakterisasi gejala serangan dan mengidentifikasi penyebab penyakit bintik batang pada tanaman buah naga. Penelitian dilakukan di kebun petani di area endemik Padang Pariaman dan Solok serta laboratorium penyakit dan molekular Balitbu Tropika sejak tahun 2014 sampai 2016. Penelitian dilakukan dengan metode deskriptif dan pengujian laboratorium. Karakterisasi gejala serangan penyakit diamati terhadap bagian tanaman yang terserang. Identifikasi dilakukan dengan pengamatan cendawan penyebab penyakit secara mikroskopis, uji postulat Koch dan uji DNA. Hasil penelitian menunjukkan bahwa gejala awal penyakit ditandai dengan adanya bintik kecil berwarna putih pada tunas muda dan buah tanaman buah naga, ditengah bintik ditemukan lubang halus seperti tusukan jarum. Gejala lebih lanjut berupa bercak-bercak yang sedikit membesar, menyatu dan bagian batang yang lunak berlubang dan hancur. Berdasarkan ciri-ciri mikroskopis dan hasil amplifikasi region ITS DNA isolat cendawan asal buah naga teramplifikasi pada 580 bp dan berdasarkan identifikasi bank gen (BLAST), sekuen nukleotida isolat cendawan menunjukkan 99% kesamaan dengan Neoscytalidium dimidiatum. Hasil penelitian ini selanjutnya dapat menjadi dasar/rujukan dalam melakukan penelitian untuk mencari teknik pengendalian di lapangan nantinya.KeywordsHylocereus spp.; Penyakit; Identifikasi; Karakterisasi gejalaAbstractDiseases are the main obstacles in the cultivation of dragon fruit plants in Indonesia. Several types of pathogens attack dragon fruit plants, but the most dangerous and detrimental disease is the stem canker. This study aimed to characterize disease symptoms and identify the causes of stem canker disease in dragon fruit plants. The research was carried out at the farmer’s farms in the endemic areas of Padang Pariaman and Solok as well as the Laboratory of Disease and Molecular Balitbu Tropika from 2014 to 2016. The study was conducted using descriptive methods and laboratory testing. Characterization of symptoms of disease was observed in the affected part of the plant. Identification is done by observing the fungus that causes disease microscopically, Koch's postulate test and DNA test. The results showed that the initial symptoms of the disease were characterized by the presence of small white spots on young shoots and fruit of dragon fruit plants, in the middle of the spots found a fine hole like a needle puncture. Further symptoms include patches that are slightly enlarged, fused and the soft part of the stem is hollow and broken. Based on microscopic characteristics and the results of amplification of the ITS region the fungus isolates DNA from dragon fruit amplified at 580 bp and based on gene bank identification (BLAST), nucleotide sequences of fungal isolates showed 99% similarity with Neoscytalidium dimidiatum. Further research is needed on the ecobiology of pathogen and effective control techniques