Abstract: A PDE-ODE model was developed to describe the spread of powdery mildew on grapevine. The model was able to retrieve the main characteristics of the system: 1) a host growing during the whole season with time evolution in susceptibility, 2) a crop highly structured in rows with potential heterogeneities of plant growth and susceptibility within and between plots. These characteristics are modified by cultural management. Simulations were performed to test the effect of grapevine spatial heterogeneities, within and between plots, on the disease spread. Heterogeneities considered were the plant growth (vigour, earliness), susceptibility (susceptible vs resistant, treated vs untreated) and the spatial arrangements (patches vs rows). The main effect on disease reduction was obtained by arrangement in rows of susceptible and fully resistant plants.