Plasmopara viticola, the aetiological agent of grapevine downy mildew (DM), is the most important pathology afflicting viticulture and requires a great number of fungicide treatments to avoid severe yield losses and quality decreasing. To date, great efforts have been made to reduce the use of plant defensive products. Resistant cultivars, new agrochemicals and, finally, epidemiological models have been elaborated to better manage plant phytoiatric treatments. Nowadays, models are widely used because they allow the cultivation of traditional varieties, limiting agrochemicals. Using such models, implemented in a DSS (Decision Support System), results in a lower risk of grapevine damage by diseases and pests and, in many cases, in a lower input of active substances. Thanks to the information reported in a DSS, users could become more conscious of the relations between weather conditions, pathogen’s cycle, and infections risk, which is an issue not yet well understood by lots of winegrowers. For this instance, DSSs have been established as important tools for the achievement of more sustainable agricultural practices. Hence, understanding their working principles might be really important. In fact, in this way, technicians and farmers can adopt the suitable system to fit their own agricultural reality, aiming at a better vineyard management under a sustainable point of view.