Abstract: Apple scab, caused by the fungal pathogen Venturia inaequalis, is considered to be the most important single disease of apple worldwide and one of the most costly to control. Currently, the strategy for apple scab control relies on multiple applications of fungicides, often 8 to 12 fungicide sprays each growing season. These sprays represent an appreciable input of costs to growers and additionally, they can have a substantial impact on the environment. A new microbial pest control agent belonging to the genus Microsphaeropsis has been isolated. The application of this agent after harvest inhibits the formation of pseudothecia of V. inaequalis and consequently reduces the amount of primary inoculum the following spring which will result in a reduced spraying schedule.