As part of its variety testing activities prior to national listing, GEVES evaluates the resistance of rapeseed to clubroot. This disease, caused by a pathogenic fungus called Plasmodiophora brassicae, causes root galls to form, disrupting plant growth and leading to significant yield loss in the field. At the request of breeders, variety listing trials are carried out with the pathotypes (race or subspecies of the fungus with different levels of virulence) which are mainly present in France. These pathotypes were identified during a previous CASDAR* R&D project (AMS** clubroot) which ran from 2012 to 2014. An epidemiological study was carried out to highlight the frequency and distribution of this pathogen on the territory. A new CASDAR project, named OPTIPLASM, in partnership with Terres Inovia and INRAE, has been initiated with the aim of stabilising the behaviour of these strains used in national listing tests.
The aim is therefore to produce strains whose behaviour on varieties is stable over time. The first year of the project has enabled the strains' production protocol to be mastered and improved. These strains must now be characterised (identification of the pathotype) and their level of stability must be determined using successive tests. A second component consists of comparing the behaviour of different varieties tested in the laboratory under controlled conditions and in the field in clubroot-contaminated plots. These comparison tests are carried out in order to study the reflection of the reality of the test carried out in the laboratory with the field and to compare the behaviour of the varieties between the two. The first results are currently being investigated, with field scoring taking place in early July 2020. A second test campaign is currently planned to be sown at the beginning of August 2020. The project’s progress is presented within the CTPS rapeseed and other cruciferous plants section at annual meetings.
*CASDAR projects = R&D projects funded by the French Ministry of Agriculture
**AMS = Methodological Support for CTPS Sections
Posted 09/01/2020 | Last modification 09/18/2020