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2009 APS Annual Meeting

APS 2009 Annual Meeting Abstract of Presentation

Spread of Xylella fastidiosa in a pecan orchard and presence of potential vectors in orchards
R. S. SANDERLIN (1), B. Li (2), R. A. Melanson (3), S. Gil (4)
(1) Louisiana State University Agricultural Center, Pecan Research Station, Shreveport, LA, USA; (2) Louisiana State University Agricultural Center Experimental Statistics Department, Baton Rouge, LA, USA; (3) Louisiana State University Agricultural Center Plant Pathology and Crop Physiology Department; (4) Louisiana State University Agricultural Center Entomology Department
Phytopathology 99:S114

Pecan bacterial leaf scorch (PBLS) disease caused by the bacterium Xylella fastidiosa is prevalent in commercial pecan orchards in the southeastern United States. In some cultivars, PBLS can cause defoliation in excess of 50% and nut yield reduction of 13–18% annually. To determine the rate and pattern of disease spread, PBLS was monitored over a 6-year period in an orchard with three cultivars beginning when the orchard was 14 years old. The first symptoms of PBLS on newly infected trees in this orchard were generally on current season vigorous growth near the tops of the trees. PBLS increased from 5% infection to 64% infection in one cultivar (Cape Fear) and from no infection to 10.5 and 2.6% in two less susceptible cultivars (Stuart and Candy, respectively) in the orchard. Analysis suggested that the pathogen was being transmitted from infected trees within the orchard with no clear indication of an outside pathogen source. The probability of a tree becoming infected was not strongly influenced by its distance from a previously infected tree. A year-long survey of five Louisiana pecan orchards revealed that several potential vectors of the pathogen were common in pecan orchards. Five species of leafhoppers were regularly detected in all of the orchards, including the glassy-winged sharpshooter, Homalodisca vitripennis, a major vector in other hosts along with the pecan spittlebug, Clastoptera achatina, recently shown to be a vector.

2009 by The American Phytopathological Society. All rights reserved.