The invention relates to 4-propargyloxy-benzyl dervatives of the general formula (I) including the optical isomers thereof and mixtures of such isomers, wherein R1 is hydrogen, optionally substituted alkyl, optionally substituted cycloalkyl or optionally substituted aryl; R2, R3, R5, R6, and R7 are each independently of each other hydrogen or optionally substituted alkyl; R4 is optionally substituted alkyl; X is O or N—R7; and R8 is a group R9 is optionally substituted aryl or optionally substituted heteroaryl; R10 and R11, are each independently hydrogen, optionally substituted alkyl, optionally substituted alkenyl or optionally substituted alkynyl; R12 is optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted aryl or optionally substituted heteroaryl; R13 is hydrogen or optionally substituted alkyl, alkenyl or alkynyl; and R14 is optionally substituted alkyl or optionally substituted amino. These compounds possess useful plant protecting properties and may advantageously be employed in agricultural practice for controlling or preventing the infestation of plants by phytopathogenic microorganisms, especially fungi.