Investigations of Pierce's disease in the Davis Mountains, Texas (Xylella fastidiosa, Cuerna costalis, Cuerna occidentalis, Graphocephala marthonensis)

Pierce's Disease of the grapevine was found to be present at the Blue Mountain Vineyard located in the Davis Mountains of Trans-Pecos Texas. Pierce's Disease is a xylem-limited disease caused by the Gram-negative bacterium Xylella fastidiosa. The bacterium is transmitted by infected leafhoppers and/or spittlebugs that feed upon often symptomless infected host plant species. Trans-Pecos Texas is considered to be a low risk area for the occurrence of Pierce's Disease. The present study serves as an investigation into the possible sources of the bacterium in Trans-Pecos Texas. Using a sweep net, members of the insect families Cicadellidae and Cercopidae were captured, identified, and preserved. Of the 14 insect species collected, three Cicadellids were suspected as possible insect vectors of Pierce's Disease: Cuerna costalis, Cuerna occidentalis, and Graphocephala marathonensis. Selected native plant species serving as possible host plants were collected for detection of X. fastidiosa using a polymerase chain reaction technique. Bacterial DNA was isolated from plant material using a modification of the QIAGEN DNA Easy Kit protocol by QIAGEN, Inc. Primer pair XF1/XF6 for the 16S rRNA gene was used. Six plant species of the 20 plant species tested positive for the presence of X. fastidiosa: Celtis laevigata, Panicum hallii, Prunus serotina, Rhus aromatica, Vitis berlandieri, and Vitis riparia.