First report of Brenneria goodwinii, Gibbsiella quercinecans and Rahnella victoriana in France
In the EPPO region, acute oak decline has been associated with abiotic factors, as well as with the presence of Agrilus biguttatus (Coleoptera: Buprestidae) and a complex of bacterial species, mainly Brenneria goodwinii, Gibbsiella quercinecans and Rahnella victoriana (see EPPO RS 2018/104, 2018/126 and 2022/134). Studies have been carried out in France to evaluate the prevalence of acute oak decline symptoms (bleeding cortical lesions with insect emergence holes and dieback) and determine bacterial species associated with these symptoms. Studies were conducted in 5 forests where approximately 20 oak trees were assessed on each site. It was estimated that on average, 37% of the oak trees showed acute oak decline symptoms. Bacterial isolates were collected from symptomatic bark samples and were identified by molecular tests as Brenneria goodwinii, Gibbsiella quercinecans and Rahnella victoriana. G. quercinecans and B. goodwinii were found in 4 forests, R. victoriana in 3 forests. All three bacterial species were detected on both Quercus robur and Q. petraea. This is the first time that these three bacteria are detected in France in association with declining oaks.
Sources
Eichenlaub L, Denman S, Brady C, Maddock D, Robledo-Garcia F, Aubert A, Husson C, Robin C (2024) First report of Brenneria goodwinii, Gibbsiella quercinecans and Rahnella victoriana in declining oaks in France. New Disease Reports 49, e12264. https://doi.org/10.1002/ndr2.12264