The HD3901 leaf wetness sensor detects the presence of condensation on its sensitive surface and has been designed to reproduce in an extremely accurate way the thermodynamic behavior of a leaf. The leaf wetness degree is a basic information in the agricultural and floriculture fields to determine the most appropriate phytosanitary treatment to prevent mold and fungal infections in general that can affect the plants and crops in the presence of condensation on the leaves. The double sensitive surface allows to determine the wetness degree both on the top and on the bottom the leaf, important feature to get accurate indications, being that the two sides of the leaf have different drying times. In order to ensure a long duration of the sensor, the surface of the sensor is specially treated to resist to the atmospheric agents and to the chemical agents present in pesticide products.