Erysiphe, widely known as powdery mildew, is a genus of fungi capable of infecting a diverse range of plants, including agricultural crops and ornamental species. These fungi are easily recognizable because of the prominent white powdery layer they create on the surfaces of infected plant leaves, stems, and sometimes even flowers and fruits. A comprehensive understanding of the life cycle and genetic characteristics of Erysiphe fungi is essential for developing effective control measures. By delving into the ecological and molecular aspects of these pathogens, we can enhance our ability to combat powdery mildew and minimize its devastating impact on agriculture and horticulture. This chapter provides an in-depth exploration of their geographical distribution, host variety, transmission methods and management strategies, encompassing both cultural and biological approaches to mitigating the effects of the disease.