FURTHER STUDIES ON THE EFFECT OF LEAF RUST ON THE YIELD, GRADE, AND QUALITY OF WHEAT

Abstract

Experiments were carried out at Winnipeg in 1944, 1945, and 1946 to ascertain the effects of leaf rust (Puccinia triticina Erikss.) on the yield, grade, and quality of wheat. Infection in the rusted plots ranged from 22% on some varieties to 87% on others. In these tests, reductions of as much as 26% in yield of straw 40% in yield of seed, 27% in kernel weight, and 3.5 lb. in bushel weight were caused by infections ranging from 78% to 87%. Lighter infection caused smaller but important reductions. Heavy infection generally reduced grades by one commercial grade while light to moderate infection caused no grade reduction. With but one exception, leaf rust decreased the percentage protein content of the seed, although in the majority of cases it increased baking strength as measured by loaf volume. The carotinoid content of the seed was invariably increased by leaf-rust infection.