The current invention concerns a composition comprising an effective amount of a dodecylguanidine or salt thereof, preferably dodine, for use in the treatment of Alternaria on citrus. The invention also concerns a method of treating Alternaria on citrus by applying a composition comprising a dodecylguanidine or salt thereof, preferably dodine, in an effective dose and the use of a composition comprising an effective amount of a dodecylguanidine or salt thereof, preferably dodine, for the treatment of Alternaria on citrus.
