Powdery mildew is one of the most damaging and common diseases of the vine, being caused by the fungus Uncinula necator. In the years with favorable conditions for the disease infection, especially for the sensitive varieties, it may produce important damages in the vineyards, because it can manifest throughout the growing season. This disease can affect from the beginning of the vegetation the young leaves and shoots, flowers and grapes in a situation of severe infection. The wine – making process is also affected and the wines are of poor quality. Sulphur-based products are contact fungicides that provide good protection against powdery mildew without polluting the environment. The mechanism of action is a multi - site, with low risk of occurrence of the pathogen resistance phenomenon. This paper highlights the effectiveness of the two sulphur – based on products in controlling powdery mildew in three vineyards where no other fungicides have been applied. The products tested in the trials were: Polisulf (sulphur 18%, calcium hydroxide 10%), Sulfomat 80 PU (sulphur 80%) and Kumulus DF (sulphur 80% - standard reference). Data obtained demonstrated that the efficacy of Polisulf and Sulfomat 80 PU was equivalent to the efficacy of the reference product Kumulus DF against Uncinula necator in vines
