Master of Science (MS)


Plant Pathology and Crop Physiology

Document Type



Xylella fastidiosa causes disease in a number of economically important crops and landscape shrubs and trees including grapevine, citrus, oleander, and sycamore. In pecan, X. fastidiosa causes pecan bacterial leaf scorch (PBLS), which leads to defoliation and reduces nut yield. No economically effective treatments are available for PBLS. In order to improve PBLS management practices, it is necessary to determine the subspecies of X. fastidiosa strains that infect pecan so potential sources of inoculum can be identified. Multiprimer PCR and phylogenetic analyses using nucleotide sequence data from the 16S-23S rDNA intergenic transcribed spacer (ITS) region and pglA consistently identified strains of X. fastidiosa isolated from pecan as X. fastidiosa subsp. multiplex. Enterobacterial repetitive intergenic consensus (ERIC)-PCR and repetitive extragenic palindromic (REP)-PCR analyses were congruent with phylogenetic analyses. REP-PCR analyses indicated genetic variation within strains of X. fastidiosa from pecan. From these same analyses, X. fastidiosa strains from sycamore, grapevine and oleander from Louisiana were identified as subsp. multiplex, subsp. fastidiosa and subsp. sandyi, respectively. This study provides additional information about the host ranges of X. fastidiosa subspecies.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Ham, Jong Hyun