The cv. BR 1 showed high sensitivity to S. rolfsii isolates (Figure 1). The DSI ranged from 26 to 98% when plants were grown in substrate and from 20 to 76%, in soil with fertilizer supplementation. The relative differences in disease severity due to fertilizer supplementation ranged from 22 to 67%, for BR 1, and 67 to 94%, to Senegal for 55 437, indicating that although BR 1 is more sensitive to the pathogen, fertilization contributed to alleviate the effect of the disease. These results confirm the findings in the literature that the incidence of infection caused by S. rolfsii is reduced in well-nourished plants (Basseto et al., 2007; Mascarenhas et al., 2003). Based on pathogenicity assays the isolate S. rolfsii - SR5 and the sensitive cv. BR 1 were chosen to further validation assay