Leaf rust of wheat, caused by the fungus Puccini recondita f. sp. tritici, can cause heavy yield losses in wheat. Growers frequently underestimate the losses caused by leaf rust because the disease never destroys an entire crop in Kentucky and seldom causes severe shriveling of the grain. Yet the disease reduces the number of Kernels per head, as well as grain test weight. Grain from severely rusted plants is also lower in protein content.
Some leaf rust occurs in the state every year, but variations in the weather and the amount of rust overwintering in the southern states produce large year-to-year differences in leaf rust development. Yield loss is most severe when the disease occurs early in the spring on susceptible varieties and continue until the crop is mature.
Hershman, Donald E., "Leaf Rust of Wheat" (1985). Agriculture and Natural Resources Publications. 41.