Effect of copper on stem melanosis and yield of wheat: Sources, rates and methods of application

Abstract

Park wheat (Triticum aestivum cv. Park) is susceptible to stem melanosis when grown on Cu-deficient soils. Three field experiments were conducted to evaluate the effectiveness of various Cu sources, using different methods and rates of application for reducing the incidence of stem melanosis and increasing the grain yield of Park wheat on a Cu-deficient Black Chernozemic soil in central Alberta. A fourth experiment determined the residual effect of Cu over 4 years. In the first experiment, Park wheat had less disease and higher grain yield when Cu-chelate solution at 2 and 4 kg Cu ha⁻¹ or Cu-sulfate solution at 10 and 20 kg Cu ha⁻¹ was applied to the soil surface and incorporated to a depth of 8 cm or was applied at these rates as a foliar spray. The foliar application, however, was phytotoxic and delayed maturity by approximately two weeks. Sidebanding Cu (4 cm to the side and 4 cm below the seed row) was least effective. In the second experiment, Cu-sulfate solution incorporated into the soil was more effective than the soil incorporated granular Cu-sulfate in reducing disease incidence and increasing grain yield in the year of application. In the following year the granular Cu was as effective as solution Cu. The third experiment showed that Cu seed dressings did not have any effect on disease incidence or grain yield of Park wheat. In the fourth experiment, the residual effect of Cu-chelate was evident four years after application. The grain yield in the fourth year was about four times that of the control.