Update of the Scientific Opinion on the risks to plant health posed by Xylella fastidiosa in the EU territory

EFSA was asked to update the 2015 EFSA risk assessment onXylella fastidiosafor the territory of the EU.In particular, EFSA was asked to focus on potential establishment, short- and long-range spread, thelength of the asymptomatic period, the impact ofX. fastidiosaand an update on risk reduction options.EFSA was asked to take into account the different subspecies and Sequence Types ofX. fastidiosa. Thiswas attempted throughout the scientific opinion but several issues with data availability meant that thiscould only be partially achieved. Models for risk of establishment showed most of the EU territory may bepotentially suitable forX. fastidiosaalthough southern EU is most at risk. Differences in estimated areasof potential establishment were evident amongX. fastidiosasubspecies, particularlyX. fastidiosasubsp.multiplexwhich demonstrated areas of potential establishment further north in the EU. The model ofestablishment could be used to develop targeted surveys by Member States. The asymptomatic period ofX. fastidiosavaried significantly for different host and pathogen subspecies combinations, for examplefrom a median of approximately 1 month in ornamental plants and up to 10 months in olive, forpauca.This variable and long asymptomatic period is a considerable limitation to successful detection andcontrol, particularly where surveillance is based on visual inspection. Modelling suggested that localeradication (e.g. within orchards) is possible, providing sampling intensity is sufficient for early detectionand effective control measures are implemented swiftly (e.g. within 30 days). Modelling of long-rangespread (e.g. regional scale) demonstrated the important role of long-range dispersal and the need tobetter understand this. Reducing buffer zone width in both containment and eradication scenariosincreased the area infected. Intensive surveillance for early detection, and consequent plant removal, ofnew outbreaks is crucial for both successful eradication and containment at the regional scale, in additionto effective vector control. The assessment of impacts indicated that almond andCitrusspp. were atlower impact on yield compared to olive. Although the lowest impact was estimated for grapevine, andthe highest for olive, this was based on several assumptions including that the assessment consideredonlyPhilaenus spumariusas a vector. If other xylem-feeding insects act as vectors the impact could bedifferent. Since the Scientific Opinion published in 2015, there are still no risk reduction options that canremove the bacterium from the plant in openfield conditions. Short- and long-range spread modellingshowed that an early detection and rapid application of phytosanitary measures, consisting among othersof plant removal and vector control, are essential to prevent further spread of the pathogen to newareas. Further data collection will allow a reduction in uncertainty and facilitate more tailored andeffective control given the intraspecific diversity ofX. fastidiosaand wide host range.