A fungicidal composition comprising a mixture of components (A) and (B), wherein component (A) defined by formula (I) is a 3,4-dihydroisoquinoline having a 1-benzimidazolyl substituent and component (B) is selected from difenoconazole, hexaconazole, azoxystrobin, fludioxonil, cyprodinil, fluazinam, isopyrazam, pyroquilon, tricyclazole, chlorothalonil, propiconazole, penconazole, fenpropimorph, fenpropidin, sulphur and Bacillus subtilis var. amyloliquefacien s Strain FZB24. The use of the composition in agriculture or horticulture for controlling or preventing infestation of plants by phytopathogenic microorganisms, preferably fungi.
