Xanthomonas citri pv. citri findings in citrus fruits imported in the Netherlands

Abstract

Xanthomonas citri pv. citri and pv. aurantifolii are responsible for citrus bacterial canker (CBC). The trade of citrus fruit is recognized as one of the seven X. citri pv. citri introduction pathways. Under the current EU phytosanitary measures the likelihood of introduction of these X. citri pathovars in the Mediterranean region with infected fruit is rated as unlikely. In order to closely monitor the commercial trade flow of citrus fruit, imported lots that contained fruits with CBC symptoms were quarantined and a sample was sent for laboratory analysis. Survey results revealed the presence of viable and highly pathogenic X. citri pv. citri isolates in 97 infected lots between 2013-2022, while X. citri pv. aurantifolii was never found. These X. citri pv. citri infected lots primarily concerned C. latifolia (64), C. hystrix (17) and C. grandis (11) fruits mainly from South America but also from several Asian countries. Additionally, a genetic characterization of these X. citri pv. citri isolates demonstrated that, although they originated from different countries, years and Citrus species, they were all highly related, with ANI-scores ranging from 99.98% to 100%. These intercepted lots containing symptomatic citrus fruits due to the presence of X citri pv. citri, underlines the importance of continued vigilance by the exporting as well as the importing countries. Import inspections of the citrus fruit trade flow for the presence of CBC symptoms and subsequent laboratory testing remains a significant tool in assessing the long distance dispersal of X. citri pv. citri.