Sour rot of grapes is becoming increasingly important disease in many winegrowing regions, while consistent chemical or biological control has not been reported. Authors evaluated relative incidence and severity of sour rot in untreated grapevines and the effect of different biologically based treatments on sour rot at harvest. Applications of Candida sake CPA-1 plus Fungicover , Ulocladium oudemansii and chitosan were carried out in an organic vineyard in Lleida area, Spain, during the 2009 and 2010 growing seasons. At harvest, incidence and severity of sour rot were assessed. Significantly higher incidence and severity of sour rot were observed in untreated plots in 2009, when meteorological conditions after veraison were warmer. All treatments including C. sake CPA-1 significantly reduced (P < 0 05) severity of sour rot in both seasons, ranging from 40 to 67% compared with the untreated control. Incidence of sour rot was not significantly reduced by any treatment. This study helps to characterize development of sour rot in the dry Mediterranean climate conditions of the experiment, whereas also represents the first report of biological control of sour rot. Treatments with the tested biologically based products are a promising strategy to control sour rot.