The article offers information on the identification of powdery mildew on parsley and fenchel plants in Brazil. Parsley is a plant utilized in gastronomy and for extraction of anetol, a phenyl propanol derivative. Fenchel is a herbaceous plant, the same with parsley, used as condiment and for medicinal purposes. Plants collected in Brazil in the area of Department of Plant Production showed a typical symptoms of powdery mildew on the leaves. Powdery mildew is a disease thought to be introduced through contaminated seeds. A study conducted on parsley and fenchel shows that powdery mildew symptoms appeared on the inoculated leaves on the plants, but not on the control plant.