柑橘毒素病及其防治法

Citrus Viruses and Their Control Measures

毒素病（Virus disease）是一種由毒素而引起的傳染病，此種毒素是由高分子量的蛋白質體及核酸所構成，非常微小，在普通顯微鏡下不能看到，但當其存在於有生命的組織內它可以繁殖，而且像病菌一樣使作物罹病。

There are more than twenty Citrus Virus diseases in the world, among which fristeza, psorosis, xyloporosfs and exocortis are the most important ones.All of these diseases are transmitted through budwocd only except tristeza can be transmitted of both oudwood and aphids. Because of the phenomenon of masking symptoms citrus plants infected by virus sometinnes show apparently healthy. In such cases, they are served as reservoirs of inoculation to spread the disease by men orother agencies from place to place or even one country to another. Based on the literatures, the virus diseases as mentioned above can be controlled through the following measures which maybe a valuable reference for adoptation in Taiwan. (1)Citrus bud-wood registration program; This is an effective measure for controlling the cicrus virus diseases. However, it will be no use to control tristeza, if the efficient vectors-the aphids, are found in the orchards. (2)Selection of tolerant rootstocks: Some citrus varieties are known tolerant to a certain virus, and therefore use of disease tolerant rootstock will be another approach to control the virus diseases. (3)Using of nucellar seedlings as bud-Wood sources: Most viruses found in citrus are apparently nottransmitted through seeds, so we can use the nucellar seedlings as budwood sources. (4)Strengtening the inspection of importation of citrus budwood or plant: Imported citrus planting materials may bring in some new virus diseases to menace the citrus growing. To avoid this danger, strick quarantine regulations should be followed. (5)Kill aphids: Some aphids can carry and transmit tristeza. 1.Director of Ferrgshan Tropical Horticultural Experiment Station.