Impact of powdery mildew and leaf rust on milling and baking quality of soft red winter wheat

Changes in milling and baking quality (especially flour yield) of soft red winter wheat can have a large economic impact on flour mills. To determine the relationship between early-season powdery mildew and late-season leaf r ust on flour yield, flour protein, alkaline water retention capacity, and k ernel texture (softness equivalent), a study was conducted over 2 years at Kinston and Plymouth, NC. Different levels of powdery mildew and leaf rust developed on three winter wheat cultivars that varied in levels of disease resistance, the presence of seed treatment, and the presence and timing of foliar fungicide application. In Kinston and Plymouth in 1989-90, where lea f rust occurred early, the softness equivalent score was lower in wheat gro wn from seed treated with triadimenol. The following year, when the leaf ru st epidemic increased later, foliar fungicide application reduced disease a nd resulted in lower softness equivalent scores in both Plymouth and Kinsto n for cv. Saluda and in Kinston for cv. Coker 983. A regression model was d eveloped to describe the relationship between the log of the area under the disease progress curves and adjusted flour yield (AM). The AM of Saluda wa s reduced in the presence of powdery mildew such that %AFY = 103.96 - 0.92 (log AUMPC).