Synopsis Powdery mildews are the group of obligate parasitic and biotrophic fungi on wide host range of plants, cause heavy damage to them. Much work has been done on the powdery mildews of cultivated plants. These fungi exhibit their Anamorph or conidial stages in the tropic and produce their sexual or perithecial stages or telemorphs in the temperate regions. Fortunately, India harbours all the climatic conditions and geographical regions of the world and helps to produce telemorphs in Himalayan region and anamorphs in the Peninsular region.

One of the authors (VBH) is engaged in the study of the Foliicolous fungi on forest and garden plants in Southern India, especially in the Western Ghats region. The other author (DKA) worked on the fungal diseases of cultivated crop plants in the Northern region of India. Both these authors have worked for more than three decades on this group of fungi, published several papers in the nationally and intentionally reputed journals. Likewise, good number of publications of powdery mildews on cultivated crops, weeds, garden and ornamental plants, forest plants have appeared. In spite of all these, we do not have a monograph of Powdery Mildews of India to identify these fungi with certainty. Till then, the present work forms a ready reckoner in the identification of powdery mildews of India.