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27 March, 2024

The fungal species that cause Phoma leaf spot and stem canker in oilseed rape are showing decreased sensitivity to some chemical controls, sparking concerns for growers in Western Europe, according to a new study.

The diseases damage brassicas and are caused by two fungal species Plenodomus lingam (Leptosphaeria maculans) and P. biglobosus (L. biglobosa). In Europe, a range of fungicides are used for control, but azoles (known as DMIs) which act as inhibitors for a fungal enzyme, are fast becoming ineffective.

“Decreased DMI sensitivity has already emerged in Australian and eastern European P. lingam populations,” says Dr Kevin King, who led the research. “However, we are now seeing it in Western Europe, which is very worrying.”

The study was based on in vitro sensitivity testing. Decreased DMI sensitivity was found in modern western European P. lingam isolates (collected 2022-23) compared to baseline historical (1992-2005) isolates. 

The genetic sequence identified as responsible for the change was associated with a 3-10 fold decrease in sensitivity to the DMIs tested. 

In contrast to P. lingam however, the same genetic sequences were absent in modern western European P. biglobosus isolates (2021-23). 

“To date, there is no evidence that sensitivity to other control agents is changing for either species,” says Dr King. “So other fungicides such as QoI (pyraclostrobin) or SDHI (boscalid) should remain effective for now – but relying too heavily on a smaller arsenal of chemicals may well generate more instances of resistance developing in future. More integrated pest control options that incorporate biological agents and different approaches to cultivation and cropping should be explored.”

The research was funded by the BBSRC under the Growing Health and Resilient Farming Futures strategic research programmes.


Dr Kevin King

Plant Pathologist


Rothamsted Research is the longest-running agricultural research institute in the world. We work from gene to field with a proud history of ground-breaking discoveries in areas as diverse as crop management, statistical interpretation and soil health. Our founders, in 1843, were the pioneers of modern agriculture, and we are known for our imaginative science and our collaborative approach to developing innovative farm practice.
Through independent research, we make significant contributions to improving agri-food systems in the UK and internationally, with economic impact estimated to exceed £3 bn in annual contribution to the UK economy. Our strength lies in our systems approach, which combines strategic research, interdisciplinary teams and multiple partnerships.
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We are strategically funded by the Biotechnology and Biological Sciences Research Council (BBSRC), with additional support from other national and international funding streams, and from industry. We are also supported by the Lawes Agricultural Trust (LAT).


The Biotechnology and Biological Sciences Research Council is part of UK Research and Innovation, a non-departmental public body funded by a grant-in-aid from the UK government.
BBSRC invests to push back the frontiers of biology and deliver a healthy, prosperous and sustainable future. Through our investments, we build and support a vibrant, dynamic and inclusive community which delivers ground-breaking discoveries and develops bio-based solutions that contribute to tackling global challenges, such as sustainable food production, climate change, and healthy ageing.
As part of UK Research and Innovation (UKRI), we not only play a pivotal role in fostering connections that enable the UK’s world-class research and innovation system to flourish – we also have a responsibility to enable the creation of a research culture that is diverse, resilient, and engaged.
BBSRC proudly forges interdisciplinary collaborations where excellent bioscience has a fundamental role. We pioneer approaches that enhance the equality, diversity, and inclusion of talent by investing in people, infrastructure, technologies, and partnerships on a global scale.


The Lawes Agricultural Trust, established in 1889 by Sir John Bennet Lawes, supports Rothamsted Research’s national and international agricultural science through the provision of land, facilities and funding. LAT, a charitable trust, owns the estates at Harpenden and Broom's Barn, including many of the buildings used by Rothamsted Research. LAT provides an annual research grant to the Director, accommodation for nearly 200 people, and support for fellowships for young scientists from developing countries. LAT also makes capital grants to help modernise facilities at Rothamsted, or invests in new buildings.