Perkembangan Penyakit Diplodia pada Tiga Isolat Botryodiplodia theobromae Path dan Peran Toksin Dalam Menekan Penyakit pada Jeruk (Citrus spp.)

Abstract

<p>Penyakit diplodia (Botryodiplodia theobromae) pada tanaman jeruk menyebar cukup luas di sentra jeruk Indonesia. Serangan parah penyakit dapat menyebabkan kematian apabila tidak dikendalikan. Tujuan penelitian adalah mengetahui patogenisitas dan peran toksin dari tiga isolat B. theobromae asal Pasuruan dan Magetan pada jeruk siam, pamelo, dan manis. Penelitian dilakukan di Laboratorium dan Rumah Kasa Balai Penelitian Tanaman Jeruk dan Buah Subtropika pada bulan November 2015 – Mei 2016. Penelitian terdiri atas dua percobaan, yaitu uji patogenisitas pada tanaman dan uji toksin kasar pada skala laboratorium. Uji patogenisitas menggunakan rancangan acak kelompok dengan sembilan kombinasi perlakuan terdiri atas tiga jenis isolat, yaitu Mg52A.1, dan Mg39.2 (asal Magetan), Ps8b (asal Pasuruan), serta tiga jenis tanaman jeruk (pamelo, siam, manis). Parameter pengamatan terdiri atas masa inkubasi, jumlah sampel nekrosis, dan luas gejala. Perlakuan pengujian toksin terdiri atas kontrol tanpa toksin, toksin kasar isolat Mg52A.1, toksin kasar isolat Mg39.2, dan toksin kasar isolat Ps8b. Aplikasi toksin dilakukan pada daun tiga varietas jeruk dengan rancangan acak lengkap, tiap perlakuan diulang tiga kali dan masing masing terdiri atas dua daun asal tanaman yang berbeda. Hasil penelitian menunjukkan bahwa masa inkubasi isolat Mg39.2 lebih cepat dibandingkan dengan isolat Mg52A.1 dan Ps8b. Ketiga isolat patogen B. theobromae asal Pasuruan dan Magetan memiliki patogenisitas yang sama dalam menimbulkan gejala penyakit pada jeruk pamelo, siam, dan manis, sedangkan toksin hanya berperan dalam mempercepat masa inkubasi.</p><p>Diplodia disease (Botryodiplodia theobromae) spread quite widely in Indonesia citrus center. Severe attacks of disease can cause death if it not controlled. The purpose of this study was determine the pathogenicity and the effect of toxins from three isolates of B. theobromae origin Pasuruan and Magetan on tangerine, pummelo, and sweet orange varieties. The study was conducted at Indonesian Citrus and Subtropical Research Institute during November 2015 – May 2016. This observation consisted of two experiments that pathogenicity test in screenhouse and crude toxin of patogen test in laboratory. Pathogenicity test used randomized block design arranged as factorial. The first factor was three isolates: Mg52A.1, Mg39.2 (from Magetan), Ps8b (from Pasuruan) and the second factor were kind of citrus (pummelo, tangerine , and sweet orange). The observation parameter consist of the incubation period, the number of necrotic samples and visual symptom. Crude toxin test treatment consists of a control test toxin without toxins, crude toxin Mg52A.1, crude toxin Mg39.2 toxin, crude toxin Ps8b. Application toxin carried out on the three leaf varieties of oranges. Each treatment was repeated three times and each consists of two leaves of different varieties. The results showed that the incubation period Mg39.2 isolates faster than two other isolates. Infection with different isolates and treatment of different citrus varieties shows that it did not different significantly in causing disease symptom of diplodia. Similarly result on crude toxin treatment with three isolates on three varieties showed that it were not different necrotic symptom. Thus the three isolates of pathogens B.theobromae origin from Pasuruan and Magetan have the same pathogenicity in causing disease symptoms in citrus pummelo, tangerine, and sweet orange. Toxin only play a role in accelerating the incubation period.</p>