Applied N and soil test K were negatively correlated with the incidence of Chocolate Spot (CS). Applied N was also negatively correlated with Northern Corn Leaf Blight (NCLB), but no relationship existed between soil test K and this disease. Levels of exchangeable K above 170 lbs/acre essentially eliminated the CS infection. Lodging of corn was positively correlated with applied N and negatively correlated with soil test K. Levels of soil test K above 170 lbs/acre markedly reduced the amount of lodging. Six different hybrids were included in this study. The hybrids showed significant differences in the incidence of the CS disease. Multiple regression equations indicated that corn yield:, were maximized at a level of 160 lbs/acre of applied N and a soil test of approximately 280 lbs/acre of K.