A synoptic review of plant disease epidemics and outbreaks published in 2023 with synthesis of trends between 2021 and 2024

Abstract We reviewed scientific literature and CABI distribution records published in 2023 to find major plant disease outbreaks and first reports of pathogens spreading in new locations or infecting new host species. This is the third in a series of studies, building on work analysing and documenting reports from 2021 and 2022. We also perform additional analyses to identify time lags between first reports of a disease in a given location and subsequent outbreaks. Pathogens with at least eight articles in the 2023 scientific literature were Xylella fastidiosa , Puccinia striiformis f. sp. tritici , Bursaphelenchus xylophilus , Candidatus Liberibacter asiaticus, Fusarium head blight pathogens ( F . graminearum and F . culmorum , which we treated as a single entity), Puccinia graminis f. sp. tritici , Phytophthora infestans , cassava brown streak viruses (cassava brown streak virus and Uganda brown streak virus, which we again treated as one) and tomato leaf curl New Delhi viruses. CABI distribution data from 2023 confirmed new reports for 38 pathogens from 88 records. Pathogens with four or more reports were Meloidogyne enterolobii , Pectobacterium brasiliense , tomato brown rugose fruit virus, Colletotrichum liriopes , Khuskia oryzae , Colletotrichum truncatum , tomato fruit blotch virus, Erysiphe corylacearum , Pantoea ananatis and Ralstonia pseudosolanacearum . As previously, there was little overlap between pathogens identified by reviewing scientific literature versus CABI distribution records. However, the set of pathogens reported in the scientific literature was relatively consistent from 2022 to 2023. Considering reports of outbreaks in the scientific literature from 2020 to 2024, we identify wide variation in intervals between the first report of that pathogen in a country and subsequent disease outbreaks. In some cases, the first report was made over a century ago (for Phytophthora infestans in Ecuador, Xylella fastidiosa in California and Fusarium spp. (pokkah boeng) in China) with major outbreaks still occurring. For other outbreaks, less than a decade had passed since the first report, including Sri Lankan cassava mosaic in Thailand, and Fusarium oxysporum f. sp. cubense in Brazil. We discuss possible reasons for – and implications of – this wide variability in intervals between first report and epidemic emergence.