First report of pecan bacterial leaf scorch caused by Xylella fastidiosa in pecan (Carya illinoinensis) in Arizona, New Mexico, California, and Texas.
In the 2015 and 2016 growing seasons, symptoms consistent with pecan bacterial leaf scorch (PBLS) were observed in pecan plantings in Arizona, New Mexico, California, and Texas, USA. Symptoms included tan to light brown necrotic lesions, which often started on the leaf margin and expanded throughout the leaflet, eventually resulting in abscission. Some leaflets exhibited tip necrosis with the end of the leaflet curling upward. The causal pathogen was identified as Xylella fastidiosa based on biochemical and molecular analyses. This is thought to be the first report of the presence of X. fastidiosa on pecan in the southwest region of the USA.