TOLERANCE TO SEPTORIA-TRITICI BLOTCH IN SOFT RED WINTER-WHEAT

Resistance to Septoria tritici blotch (STB) has not proven effective i n stabilizing yield in epidemic years. Tolerance may provide an interi m means of broad-based genetic control unit effective resistance genes can be identified. Differential loss in traits, compared to fungicide protected plots, served as the basis for evaluation of STB tolerance in soft red winter wheats. Significant variation was identified in los s-severity ratios for grain yield components, test weight and milling quality traits, in cultivars differing in resistance. It was concluded that selection under high disease pressure based on an index of low d isease rating, kernel weight and test weight would be feasible in earl y generation nurseries and should enhance STB tolerance in derived lin es.