The Citrus tristeza virus Epidemicin Bog Walk Valley, Jamaica

Abstract

In February 1997, a few trees in a grove of Valencia sweet orange on sour orange rootstock were found to be declining due to Citrus tristeza virus (CTV). This was the first grove in the Bog Walk Valley, Jamaica showing decline due to CTV. In the grove which originally had about 1,000 trees, 13 were dead and another 53 were in the final stages of decline. By August 1997, about 11% of the trees were dead and 5% were in the final stages of decline. By November 1997, an additional 25% of the trees had died, 43% were in the final stage of decline, and 25% were in early stages of decline. Only 38 trees in the original planting were rated as healthy; upon observation most of these trees had been unknowingly planted on CTV-tolerant rootstocks. By November 1997, isolated sweet orange trees on sour orange rootstock in neighboring groves were showing decline symptoms. In February 2000, the entire Bog Walk Valley was undergoing an epidemic of CTV decline on sour orange rootstock. Samples were collected from several declining trees in groves within 2.0 km of the original grove affected with CTV decline. The samples from the declining trees were tested by strain group specific probes (SGSP) and broad spectrum-, MCA13-, and orange stem pitting (OSP) -ELISA tests. All samples were broad spectrum and MCA13-ELISA positive, and several samples also reacted in the OSP-ELISA tests. In the SGSP tests, all isolates reacted with the universal probe for CTV, as well as several other probes indicating that the field isolates were composed of mixtures of CTV strains. Some of the SGSP probes which hybridized to the Jamaican isolates commonly cause stem pitting on grapefruit and/or sweet orange. OSP-ELISA tests also indicated the presence of CTV strains which commonly cause stem pitting in sweet orange indicator plants. In planta isolates are now established in the Collection of Exotic Citrus Pathogens, Beltsville, MD where further characterization will be done.

Viral Threats to Fruit and Vegetable Crops in the Caribbean

“…By 1997, quick decline symptoms became evident in Jamaica [ 39 ], and within 15 years, both quick decline and stem pitting variants were confirmed to be present across the island [ 40 , 41 , 42 ]. In phylogenetic analyses of the coat protein gene, CTV variants from Jamaica (GenBank Accession GU983384 to GU983389 and HM160500 to HM160-518) were closely related to those from other regions, indicating similarities based on biological properties rather than geographical origin [ 41 , 42 ].…”