The agar diffusion method is the most widely used because of its simplicity of implementation and low cost. According to this method, the inhibition rate for COS against T. rubrum ranged from 13.04% to 46.38% for concentrations of 0.1–1.0% after 10 d (Fig. 2). Treatments with 0.5% and 1% COS resulted in significant increases of inhibition rate (p < 0.05 and p < 0.01, respectively) in comparisonwith control. These findings indicate that COS inhibits T. rubrum growth in a concentration-dependent manner.