Location: Southern Horticultural ResearchTitle: Xylella fastidiosa is associated with reduced yield and altered fruit quality in a rabbiteye blueberry orchard in Louisiana but does not appear to spread rapidly
|FERGUSON, MARY - LOUISIANA STATE UNIVERSITY AGCENTER|
|CLARK, CHRISTOPHER - LOUISIANA STATE UNIVERSITY AGCENTER|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/1/2016
Publication Date: 4/4/2016
Citation: Ferguson, M.H., Clark, C., Smith, B. 2016. Xylella fastidiosa is associated with reduced yield and altered fruit quality in a rabbiteye blueberry orchard in Louisiana but does not appear to spread rapidly. Abstract Book XI International Vaccinium Symposium, University of Florida Gainesville, FL. Page 171. 2016.
Technical Abstract: Xylella fastidiosa is a bacterial pathogen that causes diseases such as Pierce’s disease of grape, bacterial leaf scorch of shade trees, and citrus variegated chlorosis. Work by researchers in Georgia and Florida has shown that it is the cause of bacterial leaf scorch of Southern highbush blueberries (Vaccinium corymbosum interspecific hybrids), as well, but a greenhouse experimentin Georgia suggested that it was not a major cause for concern in rabbiteye blueberry (Vaccinium ashei). In Louisiana, fruit was harvested for two years (2013 – 2014) from forty established ‘Tifblue’ rabbiteye blueberry plants. Total yield differed significantly between those in which X. fastidiosa was (5.2 kg, n = 9) and was not (12.8 kg, n = 31) detected. A marginally significant difference in average berry weight, calculated from 25 berry samples taken at each harvest, was found. Fruits sampled from one harvest date in 2014 differed in soluble solids concentration, according to a non-parametric analysis, with those from X. fastidiosa-positive plants having a higher mean soluble solids concentration (11.5%) than X. fastidiosa-negative plants (10.1%). Foliar symptoms were not always observed in association with infected plants but sometimes included early “fall” colors or, less commonly, marginal leaf necrosis. Among forty plants sampled annually, no new infections were detected in 2014 or 2015, among the 31 plants that tested negative in 2013. In repeated sampling of plants in which X. fastidiosa was detected at least once, the bacterium was detected more consistently in root sap by real-time PCR than (a) in single stem sap by real-time PCR or (b) by ELISA, in tissue from multiple petioles/midribs or most recent shoot growth (sampled when leaves were not available). Detection of X. fastidiosa by ELISA using tissue from petioles/midribs or most recent shoots seems most reliable in summer (June –September) and least reliable in April.