Disease severity was assessed using three rating classes depending on the level of sporulation as follows: 3 (resistance, R) = the resistance level of ‘Arka Manik’, no disease symptom at seedling stage, very slight colony development at juvenile stage; 5 (intermediate resistance, IR) = the resistance level of F1, few colonies present, moderate level of sporulation; 7 (susceptibility, S) = the susceptibility level of HS3355, highly profuse sporulation over the entire plants. For the genetic model of inheritance, Chi-square tests on phenotypic data were conducted to determine goodness of fit of observed to expected Mendelian segregation ratio in the F2:3 and reciprocal BC generations.