Quantitative effects of leaf and stem rusts on yield and quality of wheat

Abstract

The effects of Puccinia recondita and/or P. graminis var. tritici on the yield and quality of four Australian wheat cultivars were measured in 18 field experiments. Fortnightly applications of Dithane. S-31(R) provided almost rust-free plots for comparison with plots in which rust was allowed to develop. Leaf and stem rust intensities were assessed using the key diagram of Large and Griffin. Leaf rust caused a maximum loss of yield of 26 per cent on Mendos and 22 per cent on Gamut. Stem rust on 1156.238 caused losses of up to 49 per cent while both leaf and stem rusts on Gabo resulted in a maximum yield loss of 55 per cent. With all four cultivars, most of the yield reduction was caused by a reduction in the weight of individual grains, reflected in the losses in 1,000 grain weights. Infection by leaf or stem rust generally resulted in a reduction in bushel weight and protein content.