Rothamsted Research reported on 25 September 2026 that researchers had detected resistance to SDHI fungicides in Plenodomus biglobosus, one of the pathogens causing Phoma stem canker in oilseed rape. Laboratory screening found resistance in 95% of tested UK isolates and 6% of Polish isolates. The study linked resistance with mutations affecting the fungicide’s enzyme target.
Some isolates showed sharply reduced sensitivity under laboratory conditions, and the researchers found little evidence that the mutations impaired pathogen fitness. However, they stressed the need to determine effects on disease control in fields. The percentages describe the sampled populations and should not be presented as a census of every farm or infection.
