Co-designing deployment strategies for disease-resistant cultivars: Insights from a participatory landscape-scale modeling study with a wine cooperative

We developed, assessed and compared strategies for deploying grapevine cultivars resistant to downy mildew in partnership with a wine cooperative in France. In four action-research workshops, cooperative managers and multidisciplinary researchers jointly designed six feasible deployment strategies. These scenarios, implemented within the real cooperative landscape, involve planting resistant cultivars (RC) (i) on plots more than 30 years old, (ii) on 3.3% of the older plots every year or (iii) in no-treatment zones (due to proximity to watercourses or human dwellings), with and without a maximum percentage of RC in the vineyard. The strategies were evaluated with the landsepi model, which simulates pathogen spread and evolution in agricultural landscapes. The assessment criteria included disease control efficacy, resistance durability, decrease in fungicide use, and economic benefits for individual vineyards and the cooperative. Following these assessments, the cooperative prioritized planting RC in no-treatment zones as the most suitable strategy, considering broader practical constraints they face. These scenarios led us to study more specifically the effects of two little-studied factors: (i) whether or not fungicides are applied and (ii) the rapid or gradual deployment of RC. Fungicide application substantially decreases the risk of resistance breakdown and complements the epidemiological control provided by RC, particularly when the fitness costs of virulence are low. The probability of pathogens adapted to RC becoming established was generally lower with gradual than rapid RC deployment; however, when establishment did occur, the time to establishment was shorter for gradual strategies at a mean cropping ratio ≥ 50 % . Ultimately, these choices have a marginal overall impact on disease control due to compensatory epidemiological and evolutionary processes, including dilution effects, and the probability and timing of resistance breakdown. Our study highlights the potential of participatory approaches for developing practical, scientifically grounded strategies for sustainable agriculture.