Powdery mildew caused by Oidium mangiferae is a serious disease of Mango. Survey of the disease was conducted during seasons 2011 and 2012 in Sharkeya, Behera, Ismailía and Giza as well as Noubareya district. The highest disease severity (%) was observed in Ismailía being (46.6%) and the lowest in Giza (23.6%). Five different fungicides namely Punch, Bayleton, Kema-Z, Colis, Billis and one biocide ( AQ 10) were used as spraying treatments to control the disease on four Mango cultivars (Langara, Zebda, Alphonso and Fagri Kelan) grown at Noubareya district. Punch gave the highest efficiency in controlling the disease being (78.9 and 79.4% in 2011 and 2012, respectively) whereas AQ 10 gave the lowest efficiency (57.o % and 55.3%). Using the fungicides tested and the biocide maintained the chlorophyll content at comparative level with the healthy tissue. The untreated infected control showed reduced in chlorophyll content. The yield increased by using fungicides and biocides ranging from 307.4% to 35.5% depending on the treatment and cultivar. The increase in income occurred as a result of reducing disease severity which led to maintaining chlorophyll content and photosynthesis.