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On March 24, the Phosmet Phase-out Action Plan held a symposium in Paris to present the results of this ambitious R&D program. One of the Plan’s key focuses was on identifying ways to enhance the resilience of rapeseed, with particular emphasis on the results of the Adaptacol2 and Resalt projects.
Faced with this urgent situation, the rapeseed industry has rallied together to safeguard production and develop concrete solutions, from the field to the laboratory.
Establishment: the key stage for growing robust rapeseed
“Robust rapeseed, thanks to successful establishment, is less susceptible to pests and diseases, allows the crop to reach its full yield potential, and helps reduce the use of inputs,” explained Matthieu Loos, a development engineer at Terres Inovia.
As part of the Adaptacol2 project, to promote the adoption of robust rapeseed practices, Terres Inovia and its partners monitored plots between 2023 and 2025 to assess the factors influencing rapeseed robustness. To produce vigorous plants and reduce the damage caused by fall pests, this network of plots yielded several key findings:
• Rapeseed plants with a taproot exceeding 15 cm have significantly higher biomass per plant (+50 g/plant), highlighting the importance of soil structure quality.
• Rapeseed plants that emerged after September 1 tend to have lower biomass per plant than those that emerged earlier (-25 g/plant), so early emergence is a key factor for success.
• The highest biomass per plant is obtained in plots with a plant density of 35 plants/m² (+50 g/plant): seed rate must therefore be carefully controlled.
• Soil type remains a key factor for rapeseed growth and
biomass
Supporting rapeseed growth in the fall through fertilization and biostimulation
Observations conducted in trials and on farmers’ fields have highlighted “the close link between rapeseed biomass and the damage caused by fall insect larvae: improving nutrition to boost growth is a key strategy for limiting the impact of insect damage,” explained Cécile Le Gall, a research officer at Terres Inovia.
Also as part of the Adaptacol2 project, two approaches were identified to promote rapeseed growth: nitrogen application at planting or during the growing season, on the one hand, and the application of biostimulants, on the other.
• Nitrogen application: an observed and quantified effect of nitrogen application during the growing season or at planting on rapeseed growth helps limit the damage caused by insects in the fall. “A multi-partner network supported by Adaptacol2 has helped regional stakeholders adopt this approach and continue gathering reference data under varied conditions in preparation for PAN 8,” continues Cécile Le Gall.
• Biostimulant: No effect of biostimulants on growth, insect damage, or rapeseed yield was observed under the trial conditions. As such, these experiments were not continued.
Rapeseed that is robust due to successful establishment is less susceptible to pests
Feedback on fall fertilization and the use of biostimulants
In the Berry region, where rapeseed is a key crop in the rotation, the Adaptacol2 project on hardy rapeseed has made it possible to “bring together regional partners, test numerous approaches, build the expertise of agricultural advisors, and convey key messages to farmers,” summarized Guillaume Houivet (FDGEDA of Cher).
A rapeseed platform was established for two years. What lessons have been learned?
• Nitrogen fertilization in the fall: in limiting conditions, the applied nitrogen supports rapeseed growth during the critical period (mid-October to late November). In these cases, nitrogen applied during the growing season is more effective than nitrogen applied at planting. It helps achieve the biomass per plant needed to withstand insect attacks (50 g/plant), thereby limiting damage.
• Biostimulants: experiments have shown that they have no impact on growth, the presence of larvae, or the damage observed (bushy growth).
Improving nutrition to promote growth is a key strategy for minimizing the damage caused by insects
RESALT: The Role of Plant Breeding in Combating Winter Flea Beetles
“With the goal of promoting alternative and integrated pest management, Terres Inovia has launched a new variety evaluation methodology to address the following question: Are there significant differences in pest tolerance among the rapeseed varieties marketed in France?” asked Antoine Gravot of INRAE.
The RESALT project brought together INRAE, Terres Inovia, Innolea, and ten breeders. It aimed to investigate resistance to the flea beetle:
• in rapeseed through field damage assessment to find short-term solutions.
• in Brassica through an assessment of damage under laboratory conditions, particularly the phytochemical and genetic factors involved in resistance, for medium-term solutions.
What were the key findings?
• Shared protocols compatible with genetic approaches in the field and under controlled conditions.
• Identification of elite genotypes with contrasting behaviors. The study of these genotypes under controlled conditions must be continued.
• Identification of cabbage accessions with favorable behavior: genetic and metabolomic analyses are encouraging.
A groundbreaking R&D program with strategic implications for the industry
During the opening roundtable discussion at the symposium on the Phosmet Phase-out Plan, Terres Inovia, INRAE, Sofiprotéol, and DGEAR highlighted the challenges of this R&D program.;
- Laurent Rosso, CEO of Terres Inovia
: "Faced with this urgent situation, the rapeseed sector has been able to mobilize collectively to safeguard production and develop concrete solutions, from the field to research." - Christian Lannou, Deputy Scientific Director for Agriculture at INRAE
: “Research has been mobilized to rapidly generate useful knowledge, while opening up sustainable prospects through a better understanding of pests.” - Benoît Bonaimé, Director General of Education and Research at the Ministry of Agriculture, Agri-Food, and Food
Sovereignty: "This plan demonstrates that we can reconcile urgency and transition by co-developing effective solutions with all stakeholders." - Xavier Dorchies, Deputy Director General of Sofiprotéol
: "Collaborative innovation and combined funding are essential to preserving the sector’s competitiveness and preparing for the future."
In total, 11 projects, 30 stakeholders, and hundreds of trials were implemented. In the short term, it helped secure crops and optimize existing practices. In the medium term, it has generated new knowledge (biocontrol, varieties, pest behavior). It has also strengthened collaboration and innovation within the sector. Its method, based on co-creation and problem-solving, is now a model. The challenge now is to widely disseminate these solutions to farmers.