Mobility within tree: Low
Uptake Form: Cu2+
Function: cytochrome, enzyme
Deficiency/Toxicity Symptoms: Copper is a component of plant cytochromes and is needed for enzyme activation (Maher 2004). Copper deficiency has seen in soils with high organic matter content (> 8%) and often results in leaves becoming chlorotic and developing mottling. New leaves in peach may be narrow and elongated with wavy margins. The terminals are most affected. Wilting and defoliation may occur in severe cases. Copper deficiency is associated with Zn deficiency so can be hard to distinguish. Copper toxicity is not common. Excessive Cu in soils can lead to antagonisms with other metals (Fe, Zn, Mn).
Copper is applied as a foliar spray. Copper sulphate applied at 500 g product per 100 L of water using a gun sprayer should correct symptoms of Cu deficiency. Caution should be taken to not apply Cu to fruit during the growing season, especially Anjou pears, as fruit russeting is likely to occur. Copper sprays have been applied at green tip or as a post-harvest foliar spray when there is no risk of spray injury. Post-harvest foliar sprays may also be applied as chelates or other Cu containing compounds at recommended label rates.