A water dispersion is described comprising Bordeaux mixture characterized by a copper content from 50 to 200 g/litre and a particle size distribution such that: (i) 99.99% of the particles have a mean diameter equal to or smaller than 10 µm； (ii) the mean diameter, relative to all the particles, is 1.3 to 1.7 µm. The preparation and use as a fungicide of the above-mentioned water dispersion of Bordeaux mixture is also described.
