Responses of Sugar Beet (Beta vulgaris) to Foliar Sprays of Copper

Previous studies have shown positive yield responses from foliar copper (Cu) applications to beet. However, some of these responses may have been due to fungicidal instead of nutritional effects. Also, since these studies, national yields have increased possibly increasing the Cu requirement of the beet crop. So, between 1987 and 1990 six field experiments tested the effect of foliar sprays of copper on the yield and processing quality of sugar beet. The copper was applied as Cu oxychloride or an inorganic Cu formulation, in factorial combination with a wetter or an adjuvant. Four of the experiments were on loamy sand textured soils, the remainder on peaty soils. The Cu sprays did not affect beet yields for crops grown on the peat soils. On two of the light textured mineral soils the Cu sprays did increase yield, but there was no clear relationship between soil ethylene diamine tetra acetic acid (EDTA) extractable Cu and yield response to added Cu. There was little difference between the forms of Cu tested on yield, or between the wetter or the adjuvant. Cu sprays did not affect beet processing quality, even when large yield responses were obtained. An analysis of the geographical distribution of sugar beet quota and soil extractable Cu showed that 15% of the UK's national crop could be affected by Cu deficiency.