The incidence of BSR was observed over years in 4 historically-different planting areas i.e. land converted from rubber, cacao and swamp, and continuous oil palm replanting area. In addition, we observed the effect of surgery-mounding to the lifetime of Ganoderma-infected palms and the effectiveness of different replanting techniques on the incidence of BSR disease. The infection rate of Ganoderma was faster in oil palm replanting area at 7.68% per yr, followed by land conversion from swamp, cacao, and rubber at 4.67%, 3.81%, and 1.06% per yr, respectively. Surgery-mounding of Ganoderma-infected palms can prolong the lifetime of the infected palms with number of death palm up to 4.45%. Meanwhile, removal of Ganoderma inoculum sources during replanting contributes to lower BSR incidence in the first nine years. The lowest incidence of BSR was observed following the complete removal of oil palm debris in combination with big-hole planting system with less than 5% infected palms. On the other hand, the incidence of BSR on the individual use of big-hole planting system during replanting was at 6.29% at 9 yr after planting. The result suggests the importance of inoculum removal during replanting to prevent Ganoderma infection in the early phase of oil palm development.

Penyakit busuk pangkal batang kelapa sawit yang disebabkan cendawan Ganoderma boninense merupakan penyakit utama di perkebunan kelapa sawit di Indonesia dan Malaysia. Pada lokasi yang sama biasanya juga sering ditemukan penyakit dengan gejala busuk batang atas, khususnya di areal gambut. Penelitian ini dilakukan untuk mengidentifikasi penyebab penyakit busuk batang atas kelapa sawit secara molekuler. Sebanyak tiga sampel tubuh buah jamur dari tanaman yang bergejala busuk batang atas dan dua sampel tubuh buah jamur dari tanaman bergejala busuk pangkal batang diambil dari daerah Labuhan Batu, Sumatera Utara dan Kampar Riau. Hasil identifikasi molekuler menunjukkan bahwa semua sampel cendawan baik dari yang bergejala busuk batang atas atau busuk pangkal batang adalah G. boninense. Kata kunci: busuk pangkal batang, gambut, polymerase chain reaction, tubuh buah cendawan ABSTRACT Basal stem rot disease (BSR) caused by Ganoderma boninense is the major pathogen of oil palm in Indonesia and Malaysia. Sometimes in the same location, especially in the peatland, upper stem rot (USR) disease is also found. This research was carried out to identify the pathogen of upper stem rot by molecular approach. Fruiting bodies of fungus were collected from 3 plants with upper stem rot symptoms and 2 plants with basal stem rot symptoms from Labuhan Batu North Sumatra and Kampar Riau. Results showed that all of the fruiting body samples taken from plants with upper stem rot and basal stem rot symptoms were G. boninense.

ABSTRAKPengendalian penyakit busuk pangkal batang yang disebabkan oleh Ganoderma boninense secara kultur teknis dapat dilakukan melalui beberapa metode. Empat seri percobaan lapangan dilakukan untuk menentukan keefektifan pengendalian kultur teknis yang meliputi sanitasi sumber inokulum, sistem penanaman hole in hole, pembedahan dan pembumbunan, dan pembuatan parit isolasi. Percobaan sanitasi sumber inokulum terdiri atas sanitasi sisa-sisa akar dan penggunaan lubang tanam besar, penggunaan lubang tanam besar dan sistem tanam ulang standar sebagai pembanding. Percobaan sistem tanam hole in hole terdiri atas penanaman dengan sistem hole in hole dan penanaman standar sebagai pembanding. Percobaan pembedahan dan pembumbunan terdiri atas pembedahan dan pembumbunan disertai aplikasi teer dan Trichoderma, pembedahan dan pembumbunan disertai aplikasi Trichoderma, pembumbunan disertai aplikasi Trichoderma, dan sebagai pembanding ialah tanaman terserang tanpa perlakuan. Percobaan parit isolasi digunakan untuk membandingkan antara perlakuan parit isolasi dan tanpa parit isolasi. Insidensi penyakit busuk pangkal batang diamati setiap tahun. Hasil penelitian menunjukkan bahwa empat metode pengendalian secara kultur teknis dapat mencegah infeksi G. boninense pada tahap awal perkembangan kelapa sawit. Sanitasi inokulum mampu mencegah infeksi G. boninense hingga 2 tahun setelah perlakuan (TSP), sistem hole in hole mampu menekan perkembangan penyakit busuk pangkal batang hingga 7 TSP, pembedahan dan pembumbunan mampu memperpanjang masa hidup tanaman terinfeksi hingga 3, TSP dan parit isolasi mampu mencegah penularan penyakit hingga 2 TSP.Kata kunci: hole in hole, insidensi penyakit, parit isolasi, pembedahan, pembumbunan, sanitasi ABSTRACT Effort to manage basal stem rot disease (BSR) caused by Ganoderma boninense could be conducted through several cultural practice approaches. Four series of field experiments was conducted to observe the effectiveness of cultural practice methods for controlling the epidemic of basal stem rot due to G. boninense. Sanitation trial consisted of three treatments i.e root sanitation with big hole planting system, big hole without root sanitation, and standard replanting system as comparison. Hole in hole and standard planting system were compared in the hole in hole trial. Digging and mounding trial was conducted in four treatments, i.e. digging and mounding with teer and Trichoderma, digging and mounding with Trichoderma, mounding with Trichoderma, and infected palm without any treatment as comparison. Meanwhile, a 4 m × 4 m trench was used in the isolation trench trial. Annual observation was conducted to determine the disease incidence of BSR in each trial. Results showed that all methods could prevent palms from G. boninense infection in the early stage of oil palm development. Proper root sanitation delayed G. boninense infection until 2 years after treatment (YAT), hole in hole planting system was able to suppress disease incidence up to 7 YAT, digging and mounding was useful to prolong

Outbreak of oil palm bagwormPteroma pendula has been reported within the last few years in several plantations in North Sumatra. A study was conductedto determine the impact of P. pendula attacks on oil palm productivity. Aerial photograph was taken in November 2016 andanalyzed to determine the level of damage on each palm canopy. The damage symptoms were classified onto healthy palms ascontrol plants (score 0), mild (score 1), moderate (score 2), severe (score 3), and very severe (score 4). The sample palms wererandomly selected and observed for the sex ratio, bunch number and bunch weight at 18 months after defoliation. The attackof P. pendula at the highest level (score 4) caused a significant effect on sex ratio and the number of bunches produced. Thefresh fruit bunches production was declined 21.02–36.35% on palms with moderate to very severe attack (score 2–4). Similarpalms also have a potential case of inflorescences abortion 18.41–32.54%. However, the average bunch weight was notinfluenced by P. pendula attack.

Kejadian penyakit karat daun kelapa sawit yang disebabkan alga Cephaleuros virescens semakin meningkat di Indonesia. Kerugian karena penyakit ini pada tanaman kelapa sawit belum pernah diukur secara kuantitatif. Penelitian dilakukan untuk mengukur laju fotosintesis pada tanaman kelapa sawit umur 5 tahun dengan 3 kategori serangan yaitu ringan, sedang, dan berat. Hasil pengamatan di Kebun Kalianta  menunjukkan bahwa serangan karat daun dimulai dari pelepah bawah ke pelepah atas. Kejadian penyakit juga banyak terjadi pada permukaan atas helaian daun dibandingkan dengan permukaan bawah daun. Titik kritis serangan karat daun dimulai dari daun ke-17 ke atas yang akan menurunkan laju fotosintesis kelapa sawit. Pada daun ke-9 penurunan laju fotosintesis antara intensitas penyakit ringan ke berat sebesar 42.48% yaitu dari 15.51 µmol ke 8.92 µmol.