Tamarind (Tamarindus indica) is an important crop in the dry tropic region of Mexico. Powdery mildew (Oidium sp.) is a disease that affects this leguminous crop, and causes up to 60% reduction in fruit production. Lesions on leaves are powdery; there is production of a white mycelium with a hyphal net on the foliar surface. Hyphae are hyaline with smooth cell wall, and produce short and erect conidiophores. Conidia are hyaline, unicellular, cylindrical, in chains or singly, with an average length of 27 μm × 14 μm width. Powdery mildew has a strong relationship with the rainy season, the presence of young plant shoots, and dry days; therefore, the highest disease severity occurs during August-October. The damage caused by this disease increases in orchards that have poor agronomic management practices. The current control of the disease is mainly based on the continuous application of systemic fungicides. [ABSTRACT FROM AUTHOR]