Recently developed synthetic methodology has been exploited for the preparation of an assortment of alpha,alpha'-disubstituted disulfides including all three linkage isomeric types of alpha,alpha'-diester dimethyl disulfides. Two of the diesters are very powerful antifungal agents against Aspergillus niger and Aspergillus flavus. An alpha -ester alpha'-sulfone disulfide is the most powerful fungitoxin developed by this ongoing research effort.