Premature ripening (PR) caused by Phoma macdonaldii results in yield damage for sunflower, mainly in the SouthWest of France, a major production area. The aim of the study was to characterize and identify the effect of crop management systems on PR incidence and severity, in 2006 and 2007. This field study used artificial and natural inoculation to investigate the role of host resistance, N-fertilization and water regime in the Phoma epidemics and aimed to reveal the most critical factors responsible for the disease progress and plant injury. On both years, the susceptibility of the cultivar appeared as a main factor influencing PR. However, the most severe attacks were observed in conditions of high nitrogen nutrition, especially when it was associated with water stress after flowering.