Psyllids May Give a Year’s Warning of HLB

Ernie NeffPsyllids

psyllids
Olufemi Alabi, left, and Mamoudou Sétamou

Although huanglongbing (HLB) disease was detected in Florida citrus in 2005, the HLB bacterium wasn’t found in Texas until 2011, when scientists detected it in Asian citrus psyllids (ACP). The disease wasn’t found in Texas citrus trees until 2012, suggesting that the HLB-spreading psyllids may be used for early detection of the pathogen in newly invaded areas.

Factors influencing the spread of HLB, also known as citrus greening, are poorly understood because most research has been conducted after the pathogen has been introduced. In an attempt to change that, several Texas-based scientists surveyed commercial and residential citrus trees from 2007 to 2017. They monitored the time-course variations in the proportion of citrus trees and the ACP.

“Our study commenced five years prior to the first detection of the greening bacterium in Texas and continued for five additional years,” said Olufemi Alabi, one of the Texas A&M University scientists involved in the research. “This gave us unique opportunity to obtain a holistic picture of the progression of the disease epidemics from its onset in both commercial and residential ecologies.”

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Over the course of the decade-long study, the proportion of infected trees and psyllids increased exponentially. During that time, the number of fields and residential backyards with at least one disease-affected citrus tree reached 26 percent and 40 percent, respectively, by 2017. Research also revealed seasonal fluctuations and will provide comprehensive insight into the ongoing citrus greening epidemic in Texas. The research could offer potential lessons for California and other citrus-growing regions that have not yet been affected by HLB.

Texas A&M University’s Mamoudou Sétamou, the lead author of an article about the research, said the study suggests a flatter progression of HLB disease epidemics could be achieved by protecting new plantings from infection and use of an area-wide ACP management program. “Surprisingly, our research showed that although an exponential growth was observed in progression of infected trees in Texas, the annual rate of increase was relatively slower than reported from Florida,” Sétamou said.

Learn more about the Texas research.

Source: American Phytopathological Society

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