The Effect of Citrus Farming Practices on Huanglongbing (HLB) Disease Severity in Sambas, West Kalimantan

Beberapa praktik budidaya dilaporkan mempengaruhi kesesuaian agroekosistem bagi perkembangan penyakit tanaman. Namun demikian, praktik-praktik budidaya jeruk yang mempengaruhi perkembangan penyakit huanglongbing (HLB) dan serangga vektornya yaitu kutu loncat jeruk (KLJ) Diaphorina citri belum banyak diketahui. Penelitian ini mempelajari pengaruh praktik budidaya jeruk terhadap intensitas penyakit HLB melalui survei singkat selama dua minggu pada 37 kebun jeruk yang berlokasi di Kabupaten Sambas. Parameter pengamatan adalah intensitas serangan penyakit HLB, kelimpahan KLJ, dan praktik budidaya yang diterapkan. Pengaruh praktik budidaya terhadap intensitas serangan penyakit HLB dianalisis melalui structural equation modeling berbasis partial least squares (SEM-PLS). Hasil penelitian menunjukkan tingkat penggunaan pestisida, kualitas saluran drainase, dan kepadatan tanaman jeruk berpengaruh positif terhadap intensitas serangan penyakit HLB, sedangkan tingkat keanekaragaman vegetasi dan pemberian pupuk kimia berpengaruh negatif terhadap intensitas serangan penyakit HLB. Pengendalian gulma, kualitas tanah, dan pemangkasan pemeliharaan tidak mempengaruhi intensitas HLB. Oleh karena itu, penanaman jeruk sebaiknya menerapkan sistem polikultur, menggunakan beragam varietas, dan jarak tanam tidak terlalu rapat. Pemberian hara yang dapat meningkatkan ketahanan tanaman jeruk terhadap serangan KLJ hendaknya ditingkatkan. Pengendalian hama dan penyakit tanaman disarankan dilakukan secara terpadu sehingga insektisida hanya digunakan ketika populasi hama mencapai ambang ekonomi. Kata kunci: huanglongbing, jeruk, kutu loncat jeruk, praktik budidayaSeveral farming practices have been reported to influence the agroecosystem suitability for the development of plant diseases. However, the effect of citrus farming practices on the development of huanglongbing (HLB) disease and its vector insect, namely Asian citrus psyllid (ACP) Diaphorina citri is not widely known. This research studied the effect of citrus farming practices on HLB disease severity through a two-week short survey at 37 citrus groves in Sambas Regency. Observation parameters were HLB disease severity, the abundance of ACP, and the applied farming practices. The effect of farming practices on HLB disease severity was analyzed through structural equation modeling based on partial least squares (SEM-PLS). The results showed that the level of pesticide application, quality of drainage ditches, and density of citrus plants had a positive effect on HLB disease severity, while the level of vegetation diversity and level of application of chemical fertilizers had a negative effect on HLB disease severity. Weed control, soil quality, and pruning did not affect HLB disease severity. Therefore, citrus planting should apply a polyculture system, using various varieties, and the spacing is not too tight. The provision of nutrients that can increase citrus resistance to ACP infestation should be increased. Plant pest and disease control are suggested carried out in an integrated manner so that insecticides are only used when the pest population reaches an economic threshold. Key words: asian citrus psyllid, citrus, farming practices, huanglongbin

EFFECTIVENESS OF HUANGLONGBING VECTOR (DIAPHORINA CITRI KUWAYAMA) CONTROL IN CITRUS GROWER GROUP BASED IN SAMBAS REGENCY OF WEST KALIMANTAN, INDONESIA

The purpose of this study was to determine the effectiveness of Huanglongbing vector control based on Citrus Grower Group recommendation. Studies have been carried out in 2010 in Tebas Sungai village, Sambas district, with 11 tangerine groves owned by growers in the Citrus grower Association of Sambas district. The tangerine grove that been used are, one grower's orchard as a demonstration plot in a particular citrus grower group (orchard I); five other citrus orchards with different ownership at the same citrus grower Group (orchard II), as well as five other citrus orchard with different ownership which each of them spreads over five different citrus grower groups outside the farm demonstration plots (orchard III). The recommendation technology for controlling Huanglongbing vector which applied in this experiment, included bark painting by systemic insecticide of imidacloprid for two each 1.5-month and spray using contact insecticide with dimethoate to the plant crown which application time been alternated after bark painting application. The effectiveness of technology implementation is measured by a decrease psyllid populations found in citrus samples in adult stage, nymphs and eggs that were observed at regular intervals every two weeks during the flushing to the 14th week after the first treatment. The results showed that recommended treatment technology were absolutely proven to reduce Huanglongbing vector population in significant, namely in the orchard I, II, and III respectively at 95.3%, 84.7%, and 72% for stage adult; 97.3 %, 80%, and 100% for stage nymphs; and 98.5%, 100% and 100% for the egg stage

Pengaruh Pengelolaan Agroekosistem terhadap Kelimpahan Kutu Loncat Jeruk Diaphorina Citri Kuwayama (Hemiptera: Liviidae)

Asian citrus psyllid (ACP) Diaphorina citri Kuwayama is a serious problem in citrus because it transmits huanglongbing (HLB) disease. Agricultural practices without paying attention to the agroecosystem complexity often cause the agroecosystem more suitable for insect pests proliferation and less friendly to natural enemies. The research aims to study the effectiveness of agroecosystem management compared to conventional farming in the ACP control. The effects of both treatments on the diversity and abundance of ACP's natural enemies as well as the incidence and severity of HLB were also studied. Agroecosystem management consists of preventive and responsive actions. Preventive action was carried out through a polyculture system, planting refugia and legume cover crop, providing beetle banks, applying lime, applying organic and inorganic fertilizers, citrus pruning intensively, maintaining drainage ditches, and mechanical weed control. Responsive action is short-term control when the abundance of ACP reaches the action threshold. Responsive action was carried out through biological or chemical control. Meanwhile, conventional farming is a series of conventional farming and pest control techniques commonly applied by farmers. Each treatment was applied in three orchards of Siam Orange cv. Pontianak Citrus nobilis Lour var. microcarpa Hassk. The results showed that agroecosystem management was more effective in controlling the ACP population so that its abundance was lower and less fluctuated than conventional farming. ACP's natural enemies in agroecosystem management were also more diverse than conventional farming. The abundance of ACP's natural enemies and the incidence and severity of HLB in the two treatments were not significantly different