Identification of plant reservoir hosts of Xylella fastidiosa and natural infectivity of Oklahoma insect vectors

Xylella fastidiosa Wells et al. is the causative agent of Pierce’s disease of grape and many other plant diseases including leaf scorch of oleander, almond, pecan, and other shade trees, phony peach, and alfalfa dwarf.  This gram-negative bacterium is transmitted by xylem-feeding insects in the families, Cicadelllidae and Cercopidae.  Pierce’s disease of grape has been detected in eight counties in central and northeastern Oklahoma. We surveyed common weeds in vineyards to identify potential reservoir hosts of X. fasitidiosa.  Weedy plants sampled for this study are preferred food sources of xylem-feeding insect vectors, are commonly found in Oklahoma vineyards, and have been previously implicated as Xylella hosts: Virginia creeper, giant ragweed, wild Vitis sp., plantain, geranium, field clover, woodsorrel, and Bermudagrass. Insect vectors were collected from vineyards, taken back to the lab, and 7 to 10 adult insects were caged on alfalfa and ragweed for a 7-day acquisition access period. The indicator plants were held for two weeks after removal of insects before testing for insect transmission of X. fastidiosa. Immuno-capture multiplex PCR was used to test all plant and insect samples in both studies. We sampled from four vineyards in three counties in Oklahoma. The results will be used to develop an integrated pest management program that prevents or reduces further spread of Pierce’s disease in Oklahoma vineyards.