A method of treating a plant against a fungal and/or bacterial plant pathogen includes applying to a plant infected with a fungal and/or bacterial plant pathogen an effective amount of composition comprising a salicylate, potassium polyphosphite, and potassium phosphite. A method of fertilizing a plant and treating the plant against a bacterial and/or fungal plant pathogen includes applying to a plant an effective amount of composition comprising a salicylate, potassium polyphosphite, potassium phosphite, and potassium phosphate.