Mango, Mangifera indica L., is known to be the king of all fruits due to its delicious taste, marvelous fragrance, and beautiful appearance. However, several infectious diseases caused by many phytopathogens are deteriorating mango quality and quantity. Mango tree and fruit have been affected by about 83 diseases reported worldwide, and in Pakistan, 27 diseases are recognized as more important. Disease control always remains a challenge for the farmers to get optimum production especially due to pesticide resistance. Resistance to fungicide in current days is a major threat to plant disease management. In many cases, plant pathogen resistance could develop naturally; thus, several newly developed chemistries of fungicides remain at high risk. However, research toward an increase of resistance and delay in disease development has been undertaken. Existing fungicide chemistry, sometimes, renamed with new trade name does not satisfy the farmer to apply such fungicides for disease management. However, chemical fungicides are believed to be a significant way to control fungal pathogens or sometimes to inhibit and prevent the development of pathogens. However, due to pathogen resistance development, it is hard to manage plant diseases. Therefore, the impacts of such fungicide management in some important mango diseases are discussed in this chapter.