柑桔鱗砧病在臺灣兩種主要甜橙品種之發生與為害

Abstract

採自本省十七處柳橙、九處晚崙夏橙及三處極柑果園之接穗，經指示植物檢定結果，發現所有柳橙及晚崙夏橙果園均有鱗砧病潛伏或為害。以酸桔為砧木之甜橙樹雖然有鱗砧病存在，但外觀仍頗健全；以廣東檸檬為砧木之甜橙樹，則部分已呈現典型鱗砧病病徵，並有矮化現象。三處極柑園則未發現鱗砧病之存在。由此可知，鱗砧病確已普遍存在於本省兩種主要甜橙品種上。 The purpose of this investigation is to prove the occurrence of citrus exocortis viroid (CEV) disease in Liucheng and Valencia orange in Taiwan. Citrus seedlings of Arizona 861 selection of “Etrog” citron were used as indicator plant in the experiment. Budwoods from 29 orchards, including 17 Liucheng, 9 Valencia and 3 Ponkan, were collected for indexing the existence of the disease. Results indicated that exocortis existed in all sweet orange but not in Ponkan orchards. Field observation found that the disease showed typical symptoms on 7-8 year old infected trees grafted on Rangpur lime rootstock and caused great losses and severe stunting. Contrary, citrus trees on Sunki rootstock are symptomless carrier and grow vigorously. The incidence of the exocortis and the widespread use of Rangpur lime rootstock suggested that the original trees of both Liucheng and Valencia orange be infected with exocortis. The disease may become important and threaten the citrus industry in Taiwan.