Modelling leaf wetness duration for downy mildew simulation

In this work a physical model based on the energy balance was applied for the simulation of LWD (leaf wetness duration) on grapevine leaves. The model (SWEB), developed in the United States, was adapted for the Sangiovese variety and for use with agrometeorological data easily available from standard weather stations. The model outputs were compared both with data measured by sensors in 2002 and 2003 and with visual inspections conducted during 2003. following, all LWD data were used to feed PLASMO, an agrometeorological model for the simulation of grapevine downy mildew. The results were compared with epidemiological data observed in non treated plots to establish the impact of different LWD data on the quality of model simulations.