Since fungicidal activity of mercury compounds applied to the plant against pathogen is closely related to the protein in the plant, the fungicidal activity of mercury chloride coexisting with protein has been examined to make clear the disease control action of the compounds.
Mercury compounds were supplied to protein solutions through cellulose membrane in the present investigations, for, the chemicals which have been applied to the plant in field are probably diffused successively from the outside of the treated plant to the inner tissues. Protein solutions got an antifungal activity when mercury compouds were supplied to the protein solutions more than enough to combine with the thiol-group of the protein. The antifungal activity was probably due to the action of mercury compounds adsorbed to the protein, but not due to the action of mercury compounds combined with the thiol-group of protein.
Mercury compounds adsorbed to plant protein may play an important role on the disease control effect, for, the adsorbed mercury combine with thiol-group of the protein of causal fungus easily.