.alpha.-Amino acid amides of the formula I ##STR1## in which n is the number zero or one;R.sub.1 is C.sub.1 -C.sub.12 alkyl, which is unsubstituted or can be substituted by C.sub.1 -C.sub.4 alkoxy, C.sub.1 -C.sub.4 alkylthio, C.sub.1 -C.sub.4 alkylsulfonyl, C.sub.3 -C.sub.8 cycloalkyl, cyano, C.sub.1 -C.sub.6 alkoxycarbonyl, C.sub.3 -C.sub.6 alkenyloxycarbonyl or C.sub.3 -C.sub.6 alkynyloxycarbonyl; C.sub.3 -C.sub.8 cycloalkyl; C.sub.2 -C.sub.12 alkenyl; C.sub.2 -C.sub.12 alkynyl; C.sub.1 -C.sub.12 halogenoalkyl or a group NR.sub.13 R.sub.14 ; in whichR.sub.13 and R.sub.14 independently of one another are hydrogen or C.sub.1 -C.sub.6 alkyl or together are tetra- or pentamethylene;R.sub.2 and R.sub.3 independently of one another are hydrogen; C.sub.1 -C.sub.8 alkyl; C.sub.1 -C.sub.8 alkyl which is substituted by hydroxyl, C.sub.1 -C.sub.4 alkoxy, mercapto or C.sub.1 -C.sub.4 alkylthio; C.sub.3 -C.sub.8 alkenyl; C.sub.3 -C.sub.8 alkynyl; C.sub.3 -C.sub.8 cycloalkyl or C.sub.3 -C.sub.8 cycloalkyl-C.sub.1 -C.sub.4 alkyl, or in which the two groups R.sub.2 and R.sub.3, together with the carbon atom to which they are bonded, form a three- to eight-membered carbocyclic ring;R.sub.4 is hydrogen or C.sub.1 -C.sub.6 alkyl;R.sub.5 is hydrogen; C.sub.1 -C.sub.6 alkyl or phenyl, which is unsubstituted or can be substituted by halogen, nitro, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 halogenoalkyl, C.sub.1 -C.sub.4 alkoxy or C.sub.1 -C.sub.4 alkylthio; andR.sub.6 is a group G ##STR2## in which R.sub.7 and R.sub.8 independently of one another are hydrogen or C.sub.1 -C.sub.6 alkyl;p is the number zero or one; andR.sub.9, R.sub.10 and R.sub.11 independently of one another are hydrogen, C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 halogenoalkyl, C.sub.3 -C.sub.6 alkenyl, C.sub.3 -C.sub.6 alkynyl, C.sub.1 -C.sub.6 alkoxy, C.sub.3 -C.sub.6 alkenyloxy, C.sub.3 -C.sub.6 alkynyloxy, C.sub.1 -C.sub.6 alkylthio, halogen or nitro are valuable microbicides. They can be employed in crop protection in the form of suitable compositions, for example for controlling fungal diseases.