Scientists suggest lowering the expectations about the winter as a “recovery season” for the grapes infected with Xylella fastidiosa. In a paper published on Plant Disease, a group of researchers from the United States Department of Agriculture illustrate the results of tests on the response of three wine grape cultivars to temperature conditions representative of the San Joaquin Valley. Characterized by hot summers and mild winters, that area significantly contributes to the California grape production and has been severely impacted by the Xf-induced Pierce’s disease. Winter recovery under all treatments was generally limited, with some cultivar variation.
The authors of the paper suggest that, given the hot summer temperatures of many grape-growing regions worldwide and increasing global temperatures overall, winter recovery of grapevines should not be considered a key factor limiting X. fastidiosa spread and epidemic severity in most cases.