湖南省永州地区柑橘慢衰病与黄龙病病原鉴定及分布调查

Identification and distribution survey of the pathogens of citrus slow decline disease and citrus Huanglongbing in Yongzhou City,Hunan Province

为明确湖南省柑橘黄化症状与柑橘慢衰病和柑橘黄龙病的相关性,应用形态学和分子生物学方法对湖南省永州地区表现黄化症状的柑橘进行了两种病原的鉴定及分布调查。结果表明,造成该地区柑橘黄化现象的主要原因为柑橘半穿刺线虫和黄龙病菌对柑橘的侵染。所检样本中,柑橘慢衰病平均发生率为82.1%,土壤中的半穿刺线虫群体密度最高达到3 077条/100mL。永州地区柑橘黄龙病病菌属于韧皮部杆菌属类细菌亚洲种,平均检出率为64.3%。柑橘半穿刺线虫和黄龙病菌在柑橘园存在混合侵染现象,混合侵染率为53.6%。柑橘半穿刺线虫在永州地区柑橘产区分布广泛,是造成柑橘黄化症状的重要病因,重视并有效防控柑橘半穿刺线虫已迫在眉睫。

In order to determinate the correlation between etiolation symptoms of citrus in Hunan Province and citrus slow decline disease and citrus Huanglongbing （HLB）, leaf, root and soil samples were collected from citrus with etiolation symptoms in Yongzhou City, Hunan Province and the identification and distribution survey of two pathogens were carried out based on morphological characteristics and molecular biology techniques. The results showed that the infection of Tylenchulus semipenetrans and HLB pathogen were the main cause of etiolation phe- nomenon of citrus in this area. The average incidence rate of T. semipenetrans in collected samples was 82.1%. The highest population density of juveniles in samples was reached to 3 077 nematodes per 100 mL soil. The HLB pathogen is Candidatus Liberibacter asiaticus and the average detection rate was 64.3% in Yongzhou City. There were mixed infection of T. semipenetrans and HLB pathogen in citrus orchards and mixed infection rate was 53.6%. T. semipenetrans is widely distributed in citrus growing regions of Yongzhou City, and it is the important cause of large range of etiolation symptoms of citrus. There is extremely urgent for paying attention to and effectively controlling T. semipenetrans.