Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2007
Publication Date: 7/1/2007
Citation: Keremane, M.L., Halbert, S., Ramadugu, C., Webb, S., Lee, R.F. 2007. Use of Psyllids in Early Identification of Huanglongbing Disease of Citrus. Phytopathology, 97, No7: S70.
Technical Abstract: Huanglongbing (HLB), also known as citrus greening disease, is the most destructive disease of citrus. The disease is caused by three different species of phloem limited bacteria belonging to Candidatus Liberibacter. HLB was reported from Brazil in 2004 and Florida in 2005. Because of the non-specific nature of the disease symptoms and absence of reliable early diagnostic methods, the disease can not be identified in plants effectively until fully developed symptoms appear, thus making the management practices expensive and highly inefficient. We have developed a real-time PCR method for reliable detection of HLB from the psyllid vector, Diaphorina citri. Both psyllid nymphs and adults from several counties in Florida, with and without known HLB infection records from plants, were analyzed for the presence of HLB. In several cases, infected psyllid nymphs and adults were detected in counties which had no record of HLB being detected from plants. In one three year old grove of sweet orange, the HLB symptoms started appearing nine months after the HLB positive psyllids were found. In several other cases, older citrus trees have remained symptomless for more than 12-16 months after HLB was detected in psyllids from the groves. These results, coupled with other field observations, strongly suggest a long incubation period of over 18 months in older citrus trees. Analysis of psyllids would be useful for early detection of the HLB activity and would facilitate early development and application of management strategies.