First report of Thekopsora minima in the United Kingdom
In September 2021, rust-like symptoms were observed on northern highbush blueberry plants (Vaccinium corymbosum cv. ‘Liberty’) in a nursery in Perthshire, Scotland (GB). Two of the five plants appeared to be infected, with less than ten leaves on each plant showing symptoms. Laboratory analysis (morphology, molecular tests) confirmed the presence of Thekopsora minima (syn. Pucciniastrum minimum – EPPO A2 List). A BLAST analysis revealed 99.8% identity similarity to an isolate from Germany. Inoculation experiments showed that detached leaves of Vaccinium myrtillus (European blueberry) could be infected by T. minima (Latham et al., 2022).
Following this first record published by scientists, the NPPO of the United Kingdom added that T. minima has been detected in 8 instances, including at a growing site, retail premises, a landscaper, plant nurseries and a research institute. So far, the fungus has been detected in Kent, Dorset, Devon, Lincolnshire, Buckinghamshire and Perthshire. T. minima is under containment at the growing site in Perthshire with hygiene measures in place as well as fungicide sprays to be recommended next year. For plants moving in trade, it is recommended that leaves are removed and destroyed. Fungicide recommendations are being considered.
The pest status of Thekopsora minima in the United Kingdom is officially declared as: Present: not widely distributed and under official control.
Sources
Latham RL, Beal EJ, Clarkson JP, Nellist CF (2022) First report of Pucciniastrum minimum (syn. Thekopsora minima) causing leaf rust on Vaccinium corymbosum (blueberry) in the United Kingdom and pathogenicity on Vaccinium myrtillus (bilberry). New Disease Reports 45, e12057. https://doi.org/10.1002/ndr2.12057
NPPO of the United Kingdom (2022-02).