Developing sustainable management methods for clubroot

The project aimed to progress sustainable and cost-effective management of clubroot, through an enhanced understanding of the diversity of UK clubroot populations, and the prevalence of varietal resistance breaking strains. Secondly, the project aimed to assess the potential for targeted treatment by mapping the severity of clubroot in affected fields.
The project results have highlighted the prevalence of clubroot in the UK, the diverse nature of the pathogen population and the patchy nature of the disease in affected fields. Twenty-five fields were assessed using a standardised European Clubroot Differential Host set and 20 different pathotypes were identified, in almost equal proportion. Strains of clubroot that can overcome the ‘Mendel’ resistance to clubroot, which is present in resistant varieties like Crome, Mentor and Cracker, were found to be present throughout the UK. Soils from seventy-five fields were tested in total, using the oilseed rape varieties Mendel (resistant) and Tolken (susceptible) in bioassays. Of these, almost half
(49%) had disease severities of more than 10% in the resistant variety, as a % of what was noted in the susceptible variety, and 15% of sites gave results of over 30% disease severity.