LEAF WETNESS: AN AGROMETEOROLOGICAL VARIABLE FOR THE FORECASTING OF PLANT DISEASES

The development of many crop diseases is affected by the presence of free water on host surfaces. Leaf wetness duration (LWD) determines the number of lesions, hyphae growth, the severity and the incidence of infection cycles. The definition and the quantification of the role of LWD in disease epidemiology can be analysed by means of simulation models, representing a fundamental tool for the rationalisation of crop protection management. On the other hand, the complexity of the physical mechanisms determining LWD (water interception, evaporation and condensation) makes both measurement and estimation of this agrometeorological parameter difficult. In the frame of COST Action 718 “Meteorological Applications for Agriculture”, an expert meeting has been organised to analyse the requirements concerning leaf wetness simulation and the main problems concerning the application and use of leaf wetness sensors. The possibility of improving the applied methods has been deeply discussed, with a focus on the requirements for epidemiological applications.