Investigating And PCR Detecting Citrus Huanglongbing In Yueyang Hunan Province

Citrus Huanglongbing caused by Candidates Liberibacter is one of the mostsevere diseases. The yield and quality of effeeted citrus could be decreased, even thewhole tree died. Yueyang is on the north part of Hunan, which introducedmassively Guangximiyou polemoes from Fujian Province on the middle of90's. Now the total plant area of Guangximiyou polemoes is about 200 hm~2. Butin recent years, some Guanxinmi polemo trees were found the phenomenonthat leaves become yellow, fruit size become small, evensome trees weredied and citrus orchard was destroyed. The symptom is extremely similarwith citrus Huanglongbing. To confirm the reason and rule ofHuanglongbing. This research has carried on field investigation and PCRdetecting from 2004 to 2006 in Yueyang citrus orchard. The result isfollows:1. The symptom of fruit, leaf, trunk and branch whichis similar tocitrus huanglongbing was investigated and analysised, Guanximiyou polemocitrus have three leaf yellowe symptom. At the first stage, leaves onone or two of branch become blot yellowe or yellowe. Then, virus infectedtrees' fruit become small, some fruit become abnormal, and some trees arelower than normal trees. We can use this kind symptom to diagnose citrushuanglongbing.2. The PCR detecting result which come from sweet orange, SatumaMandarin,Ponkan,navel orange,Hu You polemo,and Nanfeng Mandarin issimilar to the control, five varieties are not infected by citrusHuanglongbing virus.3. The Diaphorina citri was not be found in Yueyang county, According toPCR detecting and investigating result, citrus Huanglongbing can not bedisseminated between different varieties in the same orchard, so thereason of Huanglongbing in Guanximiyou pomelo is graft.4. According to the investigating and PCR detecting result, this paperproposed a measure to control citrus Huanglong spreading in Yueyangcounty.