Submitted to: Plant Disease
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/12/2005
Publication Date: 5/1/2006
Citation: Damsteegt, V.D., Brlansky, R.H., Phillips, P.A., Roy, A. 2006. Transmission of xylella fastidiosa wells, causal agent of citrus variegated chlorosis, by the glassy-winged sharpshooter, homalodisca coagulata say. Plant Disease 90:567-570 Interpretive Summary: A bacterial disease of citrus called 'citrus variegated chlorosis' is causing serious losses in sweet orange production in Brazil and Argentina, the only countries with the disease at this time. The bacterium causing the disease is one of the Xylella fastidiosa types that cause disease in a wide range of woody plants. The bacterium is limited to the xylem (water-conducting) tissue and is transmitted by several different leafhoppers in South America. We had shown earlier that leafhoppers in Florida could transmit the bacterium from orange to orange with as few as one leafhopper. Another leafhopper, the glassy-winged sharpshooter, has become a serious problem of grapes and citrus in California and we have demonstrated that the glassy-winged sharpshooter can also transmit the citrus strain of X. fastidiosa. It is not an efficient vector but with the high populations of the insect in California, it can be an effective vector.
Technical Abstract: Citrus variegated chlorosis (CVC), caused by Xylella fastidiosa (Xf), is a serious disease of citrus in Brazil and Argentina. The pathogen is transmitted by several sharpshooter leafhopper species, including Oncometopia nigricans Walker. The glassy-winged sharpshooter (GWSS), Homalodisca coagulata Say, is a serious new pest of citrus and grapevines in California, where it transmits Xf strains to several crops including grapes, alfalfa, and almonds. Transmission studies over a three-year period at the USDA BSL3-P containment facility at Ft Detrick, MD, utilizing CA field-collected GWSS, a Brazilian strain of CVC, and Madame Vinous sweet orange seedlings, have shown consistent, though inefficient transmission of CVC. Test plants were observed for CVC symptoms, analyzed by ELISA, PCR using species-specific primers for Xf, membrane entrapment immunofluorescence (MEIF), and scanning electron microscopy (SEM). No Xylella were detected in field-collected GWSS but were detected in GWSS following feeding on CVC-infected source plants.