Modelling leaf wetness duration and downy mildew simulation on grapevine in Italy

In this work a physical model based on the energy balance was applied for the simulation of LWD on a grapevine (Vitis vinifera). The model, developed in the United States on the cultivars Chardonnay and Concord, and in Australia on Cabernet Franc, was applied for the Sangiovese variety and was adapted for use with agrometeorological data easily available from standard weather stations. The model outputs were compared both with data measured by sensors in the 1995–2003 period and with visual inspections of LWD conducted on vines during 2003. Following, simulated and recorded LWD data were used as input by a model for the simulation of grapevine downy mildew (Plasmopara viticola) and the results were compared with observed data in order to establish the impact of different LWD data on the quality of model simulations.