Abstract:In order to provide practical detection approach for early diagnosis and dynamic monitoring of citrus huanglongbing (HLB) pathogen. The sensitivity, specificity and accuracy of 3 type PCR approaches were compared. Total 425 suspected citrus samples with or without symptom of HLB from plantation of Hepu County,Guangxi were amplified and confirmed by nested-PCR and SYBR GreenⅠ-qPCR (SGⅠ-qPCR). The effectiveness and the positive rates of the two PCR were evaluated. The results showed that the detection sensitivity of SGⅠ-qPCR for HLB pathogen DNA was 10 ag/μL, while was 100 ag/μL for nested-PCR. Conventional PCR detection sensitivity was 104 times lower than nested-PCR method. Positive rate percent of detection for suspected citrus samples were in 46.6% and 40.0% by SGⅠ-qPCR and nested-PCR, respectively, which indicated that SGⅠ-qPCR was able to provide more accurate diagnoses than nested-PCR. The sensitivity and veracity of conventional PCR, nested-PCR and SGⅠ-qPCR system were enhancing in turn. Practically, SGⅠ-qPCR should be concerned priority selection in large scale early diagnosis and dynamic monitoring in citrus plantation. As the PCR instrument of quantitative detection not available, nested-PCR could be used for better detection of HLB as long as well controlling of the air pollution of amplified procedure, in order to prevent the false positive amplification.