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Xylella fastidiosa biology and ecology

Xylella fastidiosa biology and ecology. Matt Daugherty Department of Entomology UC Riverside. vector. host. pathogen. Xylella vectors. Xylella host species or varieties. Xylella strains. Xylella fastidiosa: The early years Anaheim vine disease -1882

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Xylella fastidiosa biology and ecology

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  1. Xylella fastidiosa biology and ecology Matt Daugherty Department of Entomology UC Riverside

  2. vector host pathogen

  3. Xylella vectors Xylella host species or varieties Xylella strains

  4. Xylella fastidiosa: The early years Anaheim vine disease -1882 -30,000 - 40,000 acres lost -50 wineries closed Pierce investigated viticulture, climate, epidemiology Vector and pathogen not known -thought to be a virus Isolated, identified as bacterium in 1978 Newton B. Pierce

  5. Xylella fastidiosa biology Xylem-limited bacterium Wide host range -crops, native, ornamental, weedy plants -disease severity differs among hosts Substantial genetic variation -host-specific strains -pathogenicity varies among strains Transmitted by xylem-sap feeders -sharpshooters are most important vectors -many sources of variation No cure

  6. First described in Southern California (1882) Prevalent throughout California, except -mountains -far North? AZ, Gulf states, up to Virginia Costa Rica Brazil Europe

  7. Xylella fastidiosa transmission • No latent period • Nymphs & adults can transmit • -no transmission after molting • -persistent in adults • Species differ in efficiency • Efficiency tied to plant infection level • > 10,000 cells/g plant

  8. Mechanism of pathogenicity 1. Vessel occlusion -bacterial aggregates -restricted water flow -water stress symptoms 2. “Phytotoxin” -toxin not known

  9. -X. fastidiosa growth depends on temperature

  10. Cold • mean daily min/max: • 17/24°C -mean daily min/max: 21/36°C Hot

  11. Overwinter recovery from infection • -depends on timing of inoculation • -more recovery in colder climates?

  12. Host range 100+ described plant species, from 30 plant families -most do not host Xylella or show no symptoms -some are susceptible Crops Grape Alfalfa Almond Peach Plum Olive Pecan Pear Coffee Citrus Wild/escaped grape Himalayan blackberry Periwinkle Spanish broom Black mustard … Weeds Ornamentals /natives Oleander Sweet gum Oaks Maple Elm …

  13. -grape varieties exhibit a wide range of symptom severity

  14. Identifying X. fastidiosa reservoirs 1. preferred feeding hosts of vectors? 2. high infection levels? 3. systemic infection? Not known for most landscape and nursery plants

  15. Management in Northern California vineyards -vector resides in riparian corridor -sweeps seasonally into vineyards -management targets riparian hosts

  16. Control is achieved by targeted removal of key hosts for pathogen/vector

  17. Xylella fastidiosa genetic variation Host-plant associated pathogen strains 3+ groupings in the U.S. -grape, almond -almond, oak, peach, plum -oleander Strains are biologically distinct

  18. Variation in Xylella pathogenicity Gr Alm Infection ≠ disease -not all strains cause disease in other hosts -even closely related strains may not be equivalently virulent x Gr Ole x Cit Cof

  19. healthy Strain variability for alfalfa dwarf -alfalfa is susceptible to both grape and almond strains -grape strains are more virulent than almond grape strain healthy almond strain

  20. -grape strains produce higher infection rates -grape isolates cause more severe water stress

  21. Transmission depends on: -host plant type -X. fastidiosa strain Determined by infection level Proportion transmitting

  22. Disease management Landscape management -remove alternative hosts -remove diseased vines (roguing) Develop resistant host varieties -back-crossing with resistant varieties -GMO approach (DSF, or PGIP mutants) Avirulent/symbiotic strains -outcompete X. fastidiosa

  23. Disease severity and reservoir status are affected by: • Host plant species or variety • X. fastidiosa strain • Disease management requires improved knowledge of “problematic” hosts and strain prevalence

  24. http://www.cnr.berkeley.edu/xylella/ http://xylella.org http://www.piercesdisease.org/ http://www.cdfa.ca.gov/pdcp/ http://cisr.ucr.edu/

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