The pathogenicity of three strains of SMV did not produce the protective interaction, when they were inoculated mixedly. Following Strain 1, when strain 3 was inoculated, the pathogenicity of strain 3 existed some interference from those of strain 1. Seeds collected from the infected plants inoculated by mixed Strain 1 with Strain 3 were planted. The seedling of seed borne SMV presonted same symptoms as those from inoculated with strain 1 only, and still appeared interference with strain 1 to strain 3. The plants inoculated mixedly with two or three strains had. more significant Symptom than those of with a strain only. Resistant character of varieties to SMV could be showed by the identification of resistance on varieties inoculating with mixed strains.