Increased inhibitory effect of cation as a clay-complex on fungi

The toxic effect of Ni, Cu, Ag, Cd, and Zn adsorbed to clay minerals on six fungal species was studied. In some cases the ions adsorbed to the clay were more effective as growth inhibitors than those in solution. This phenomenon was especially prominent with Cu and Ag. Though Ca was found to be non-toxic to the fungi, Ca-clay complexes inhibited fungal growth. It is postulated that clay may inhibit fungi through: (1) adsorptive effects when the cation is non toxic; and (2) direct heavy metal toxicity.