P-621 - Caught in the spray: The movement of aerosolized Xanthomonas euvesicatoria pv. perforans in tomato fields

Bacterial spot of tomato, caused by Xanthomonas euvesicatoria pv. perforans (Xep), remains a major threat to tomato production in Florida. Growers rely on chemical bactericide applications delivered by tractor-mounted sprayers operating at pressures ranging from 1379 to 2068 kPa. However, recent studies showed that Xep can become aerosolized during mock spray applications with water at 1379 kPa, raising concerns about the potential spread of Xep during routine sprays. This study aimed to quantify the dispersal of viable Xep cells during mock spray applications at 1379 kPa using passive and active sampling. Field-grown tomato plants were inoculated with a rifampicin-resistant Xep strain. In Spring 2024, aerosolized bacteria were captured using passive sampling by placing nutrient agar plates amended with rifampicin and cycloheximide 1 meter above ground at distances of 1, 2, 4, and 7 meters from inoculated plants. Xep colonies were recovered at all distances, with the highest levels at 1 meter. In Spring 2025, active sampling was conducted using 20 air sampling towers equipped with 3D-printed cyclonic samplers (270 L/min). Towers were positioned at 1, 4, and 7 meters from the plants, with samplers placed at heights of 1, 3, and 5 meters to assess horizontal and vertical movement of aerosolized Xep. Our findings confirm that aerosolized Xep can spread several meters during spray applications. These results highlight the need to refine spraying practices to minimize unintended pathogen spread and improve disease management strategies in tomato production.