From a design principle described in an earlier paper, a new series of substituted aryl methyl disulfides have been prepared and tested against Aspergillus niger and Aspergillus flavus. Methyl p-nitrophenyl disulfide is more potent (by an order of magnitude) than the fungitoxic natural product (CH3SCH2S)2. With the present rationale in hand, one can anticipate which Polycarpamine is an effective antifungal agent.