Abstract: During the past five years, systematic operations have been carrried out to prevent and cure the powdery mildew of chestnut saplings. Both field tests and laboratory analgses demenstrat that thanks to the improvement of the cultivation control and of the irrigation during dry seasons as well as the betterment of illumination and aeration, and thanks to the use of Bordeanx mixture during growing seasons and lime sulphur, rest seasons, and also thanks to the more importance attached to preventing the spread o...