Social learning and the diffusion of innovations through peers are key components of agro-ecological transition, as they contribute to the generalization of good practices and improve the efficiency of public policies by increasing the number of farmers reached at no additional cost. We evaluated the spillover effects of a pesticide reduction scheme, implemented in France during the 2010s, which was designed to train farmers in pesticide-saving practices and encourage knowledge diffusion beyond the scope of enrolled farms. We estimated a fixed-effect model using pseudo-panel data collected at the national scale and found that doubling the share of enrolled farms within cohorts would reduce pesticide use by 7.3% to 10% on average. We found an additional effect of a similar magnitude when doubling the share of farms attending demonstration days hosted by farmers trained through the program, this impact being all the stronger as the share of enrolled farms is high. These results suggest that agricultural training programs with peer-sharing component are likely to generate spillover effects and increase the adoption of new practices at a lower cost than traditional programs.