A method of controlling diseases on barley plants caused by phytopathogens, which comprises applying to the barley plants or to the locus of the barley plants a combination of cyprodinil and an unsaturated C 18 -fatty acid selected from oleic acid, linoleic acid and linolenic acid, wherein the weight ratio of cyprodinil to oleic acid is from 100 : 1 to 1: 100.