Abstract
An increased occurrence of the fungal disease Alternaria blotch of apple, sometimes resulting in severe production losses, has been observed in South Tyrol in recent years. In integrated production, up to now the disease could be effectively contained with the fungicides currently available on the market. The studies conducted in 2010 and 2011 aimed at evaluating the efficacy of several plant protection products allowed in organic farming against Alternaria blotch of apple. Lime sulphur and acid clay were tested in both 2010 and 2011. Potassium bicarbonate was tested only in 2010, while algae extract and copper sulphate were tested only in 2011. Up to now, satisfactory results were obtained only with the acid clay-based product Ulmasud.