Addressing gaps in the ecology of Xylella fastidiosa and its vectors in diversified cropping systems

Xylella fastidiosa (Xf) is a plant-pathogenic bacterium that causes disease in numerous crops including grapevine, peach, citrus, olives, and blueberry. Xf is xylem-dwelling and is comprised of at least three major subspecies, two of which (subspecies multiplex and fastidiosa) are known to occur in the Southeast U.S. Xf is transmitted by various sharpshooters and spittlebugs, in which the bacterium forms a biofilm within the insect mouthparts and foregut. In South Carolina, many fruit producers are growing multiple Xf-susceptible fruit crops in combinations to diversify production and fill local needs. However, there is a lack of understanding which Xf subspecies and vectors are present in these diversified cropping systems, and if and when the vectors are transmitting Xfm and Xff within and between crops. We conducted a survey for Xf in 2023 across 10 farms and including 8 different crop hosts and identified Xf in 193/371 (52%) of these plants. In 2024 we have selected three farms to monitor insect vector dynamics and their viruliferous status. Ultimately this research will help us determine which crops might be risky to grow in combinations and where Xf and vectors would need to be more closely monitored.