Dissemination of Citrus Greening in Puerto Rico

Abstract

Citrus Greening (CG) caused by a phloem restricted bacteria, Candidatos Liberibacter asiaticus (Ca. L. asiaticus), is one of the most devastating diseases of citrus worldwide. The disease dramatically affects the production of citrus trees. Following the detection of CG in Puerto Rico, a survey was conducted from February 2011 to March 2012 to determine the dissemination of the pathogen. Twenty orchards and seven nurseries located in the central mountain region, southern coast, northern and northwestern region of the island were sampled. Symptomatic and asymptomatic plants were collected and processed at the plant disease clinic of the University of Puerto Rico (UPR) Agricultural Experiment Station in Juana Diaz, Puerto Rico. A total of 345 samples were analyzed by Polymerase Chain Reaction using primers 011 and OI2. Citrus Greening was detected in only 7.0% of the symptomatic samples collected in eight orchards covering an area of 235 hectares in the municipalities of Adjuntas, Añasco, Cabo Rojo, Coamo, Dorado, Juana Díaz, Las Marías and Santa Isabel. In 42 samples negative for Ca. L. asiaticus, two additional diseases were tested by serological methods: Citrus Tristeza Virus (CTV) and Citrus Variegated Chlorosis (CVC). Both diseases were detected: CVC in a sample from Ciales, CTV in 41 samples from various municipalities. Regular screening of Ca. L. asiaticus in orchards and nurseries, vector control strategies and removal of CG infected trees should be implemented to protect the citrus industry on the island.