Black Mildew's are the very specific group of ascomycetous fungi having interesting miro-morphological characters. Tiny colonies on living leaves show microscopic ornamental structures. Though, Western Ghats of India are not much explored, appears to be hub for these types of fungi, especially Mahabaleshwar, which is known for tourist place and its huge biodiversity. Present work is the systematic documentation of black mildew's representing to contemporary research in mycology highlighting issues of untapped diversity and ecology of Black mildews fungi. Each taxon is well described with appropriate line drawings, photo-micrographs, identification key, and specific ecological note. The mounting technique of the black mildews is interesting and speciality of this work. As such, this work provides a baseline data to ease their identification in the field, as well as in the laboratory. This work will become asset for the researchers, teachers, students and foresters.