Large-scale surveys of leaf lesions on potato in the period of 2009-2012 showed that many symptoms were not caused by Alternaria solani, but were of physiological origin. As a large percentage of these lesions contained the fungus Alternaria alternata, the question arose whether or not A. alternata is capable of causing necrosis. In this study we show and confirm that A. alternata appears to be unable to infect potato leaflets and cause lesions, suggesting there is no need to specifically treat against this saprophytic fungus