field or lawn of grass the aqueous solution in this embodiment is applied in an amount which is sufficient to penetrate beneath the thatch layer of the grass but is insufficient to significantly reduce or retard the growth of the grass or impair its color the concentration of the aqueous solution consists of about 0 25 to 25 methylammonium methyldithiocarbamate by weight the remainder being water the preferred application rate is about 0 5 to 20 lbs of methylammonium methyldithiocarbamate by dry weight per treated acre of soil methylammonium methyldithiocarbamate generally retains its fungicidal activity when applied at these rates in addition to the preferred concentration and application rates described above one can effectively employ the methylammonium methyldithiocarbamate at higher concentration rate in such applications the preferred method is to add additional water to the field to move the more concentrated solution into the root zone of the plants these and other embodiments of the invention may be better understood in connection with the following representative example which is presented for purposes of illustration of the invention and not by way of limitation the effect of the application of methylammonium methyldithiocarbamate to live grass was determined in the following manner dilute aqueous solutions of three salts of the same dithiocarbamic acid derivative were prepared methylammonium methyldithiocarbamate sodium methyldithiocarbamate and potassium methyldithiocarbamate the solutions were prepared by mixing the dithiocarbamic acid derivative with water to achieve a concentration of between about 1 2 and 3 5 by weight three plots of grass of substantially equal type quality color and size were selected at each of several golf courses throughout the state of florida the grass at these.