However, Leveillula taurica (Lev.) Arnaud (anamorph, Oidiopsis haplophylli Rulamort) is the most prevalent and economically damaging powdery mildew agent to tomato. L. taurica is an important pathogen on the crop in dry conditions, when air relative humidity (RH) is between 50 and 70%, and temperatures are between 20 and 25 C