Abstract: Brown spot of pear is caused by the fungus Stemphylium vesicarium (Wallr.) Simmons, and produces high economical losses in several pear-growing areas in Europe including Spain, Italy, France, The Netherlands, Belgium and Portugal. The management of the disease is based on protective fungicides applied at fixed schedule or according to the BSPcast model. But, the efficacy in disease control is limited, especially when disease pressure is high. In order to reduce the disease pressure, additional methods focused to reduce the inoculum may be incorporated in the integrated control. To characterize the inoculum, populations of S. vesicarium from different pear orchards in Girona (Spain) were characterized for their pathogenical activity. Additionally, the dynamics of S. vesicarium inoculation under natural conditions were determined. On the other hand, S. vesicarium overwinters on pear in fallen infected leaves or fruits as pseudothecia of its teleomorph Pleospora allii, the relationship between disease levels at leaf fall and the production of pseudothecia was determined.