Designing Wheat Variety Mixtures to Reduce Septoria Leaf Blotch Epidemics: Theoretical Approach and Field Experiments

This study combines field trials and modeling to design wheat cultivar mixtures that control septoria leaf blotch, a splash-dispersed fungal disease. Over five years, plots mixing one susceptible and one partially resistant variety showed disease severity reductions up to 50%, varying with annual disease pressure. Trials of four-way mixtures (2010–2012) reduced fungicide use by about 5% without yield loss, while fungicide-free plots gained 0.23 t/ha compared to pure stands. A simulation model of spore dispersal by raindrops determined optimal variety proportions based on partial resistance levels. This pre-sowing practice offers agronomic benefits under foliar disease pressure and no penalty when disease is absent.