containing compound most preferably in a weight ratio of the iodine containing compounds to the chlorite salts of from 0 001 0 005 to 0 0001 0 05 preferred iodine containing compounds include lithium iodate sodium iodate potassium iodate ammonium iodate lithium periodate sodium periodate potassium periodate and ammonium periodate most preferred are iodic acid periodate dihydrate potassium iodate and sodium iodate the composition of the invention further comprises at least one solvent preferred solvents include water ethylene glycol propylene glycol dipropylene glycol polypropylene glycol diethylene glycol triethylene glycol 1 5 pentanediol 2 4 pentanediol benzyl alcohol and mixtures thereof the method of the present invention for preparing isothiazolone containing compositions comprises adding 3 isothiazolone compounds of formula i a metal nitrate and a magnesium chloride to a solvent to prepare a mixed solution then at least one of the iodine containing compounds is mixed with a chlorite salt the resultant mixture is added to the solution containing 3 isothiazolone prepared in the foregoing step the present invention further provides a method for suppressing the growth of microorganisms derived from animals and plants for example bacteria fungi and algae according to the present invention the growth of microorganisms may be inhibited or the microorganisms may be killed the isothiazolone containing compositions of the invention may be introduced into the habitats of any microorganisms including cooling towers air washers boilers mineral slurries wastewater treatments ornamental fountains reverse osmosis filtration systems ultrafiltration systems ballast water evaporative condensers heat exchangers pulp and paper processing fluids plastics emulsions and dispersions paints latexes coating agents and metal working fluids to better define the present invention the following examples are set forth these examples are only to better the understanding of the.