The invention relates to a plant protecting composition or agricultural pesticide, comprising a substance which is selected from the group comprising poly(alkyl)guanidines, poly(alkyl)biguanidines, polyguanines or octenidin, or any blends of substances of this group. In a preferred embodiment, the substance which is selected from the group comprising poly(alkyl)guanidines, poly(alkyl) - biguanidines, polyguanines or octenidin, or any blends of substances of this group, is present in combination with at least one other component exhibiting activity against agricultural pests. Said least one other component exhibiting activity against agricultural pests may represent at least one active agent of a commercially known pesticide. A further aspect of the invention relates to a method for protecting plants against plant pathogens comprising the application of the above agricultural pesticide compositions.
