Professor UC Berkeley Berkeley, California, United States
Abstract Text: Xylella fastidiosa-infected grapevines may recover from infections over the winter in a phenomenon known as winter recovery. This is currently the only known cure for Pierce’s Disease. Winter recovery is thought to limit the northern range of the causal pathogen and lower the incidence of chronic disease in cooler climates. Despite its importance to the ecology and management of the disease, very little is known about the biology of winter recovery. We conducted a series of experiments over two winters to compare recovery across different infection levels at three different locations in Northern California. Plants were removed four times over the course of the winter to create a range of cold exposure treatments. Across all locations and removals, plants with lower levels of infection in Fall, estimated from qPCR results, were more likely to recover over the winter than plants with higher Fall bacterial populations. This trend also held across six other grapevine varieties in a separate study. These results suggest that recovery has a quantitative component, in that pathogen population size appears to impact winter recovery rate. Future work aims to exploit these findings to determine whether methods that reduce bacterial populations in the Fall, when paired with winter exposure, can result in higher rates of winter recovery from infection.
