柑桔黃龍病之感染與防治

Abstract

柑桔木蝨（Diaphorina citri ）傳播之黃龍病（huangiongbing ）為柑桔之重要病害，由一種多型性的擬細菌（Fastidious bacteria ）所引起，植株受感染後經過一段時間，病原將分布整個植株，屬於系統性病害。柑桔黃龍病目前尚無有效之治療藥齊j ，注射抗生素如四環黴素雖會得到暫時性的舒緩效果，但卻無法完全根治。種植無病健康苗、防治柑桔木蝨及砍除田間病株為防治的基本原則。但田間實際狀況非常複雜，唯有對病原菌、媒介昆蟲及其相關之環境因子作通盤了解，方能適時作出有效防治。黃龍病病原菌不經木蝨卵傳播，木蝨一旦獲毒即終生帶毒，若蟲之獲毒能力佳，成蟲獲毒能力差，荒廢柑園則是孕育帶毒木蝨的最佳場所。黃龍病的防治首應注重荒廢柑園的清除，避免帶毒木蝨遷飛侵入附近果園造成感染。其次針對柑桔木蝨之遷飛期與發生期進行藥劑防治，避免木蝨在芽期大量繁殖而造成柑園內黃龍病之蔓延與流行。若能做好柑桔木蝨的防治工作，再加上種植健康苗與清除田間病株，即可有效減少黃龍病之發生。 Huanglongbing (HLB) is an important systemic disease of citrus. It is caused by the fastidious bacterium that is transmitted by the insect vector, Diaphorina citri (Kuwayama), with a persistent but not transovarial manner. The acquisition efficiency of HLB bacteria in nymphs seems to be better than that in adults. It is necessary for efficient control of HLB to study the epidemiology associated with interactions among pathogens, vectors and climatic factors. Diseased citrus trees usually become the most important source of inoculum. It is essential to limit inoculum for the control of the disease. The efficiency of HLB control depends on the successful elimination of inoculum. Control of HLB can be achieved by several methods such as eradication of infected plants, elimination of the insect vector and cultivation of pathogen-free seedlings. Application of antibiotics in HLB-infected trees may alleviate symptoms but not eradicate the HLB bacteria. Long-term treatments with tetracycline also resulted in chemical injury in citrus plants. Tetracycline is considered to be bacteriostatic for HLB bacteria, and it needed to be applied regularly to continue its effect. It is therefore harmful to environment and easily causes the emergence of antibiotic-resistant bacteria.