Copper sulphate is commonly used in gardening and agriculture as a fungicide and fertiliser. Used in the correct concentrations, copper sulphate prevents damage to plants from mould and fungi. Plants growing in soils that are deficient in copper will benefit from the application of a copper sulphate-based fertiliser. However, overuse of copper sulphate -- or other copper-based products -- can cause a toxic build-up of copper in the soil, resulting in a variety of negative effects.
Copper sulphate-based fertilisers and sprays are commonly used to correct copper-deficient soils. When used in the correct amounts, copper sulphate prevents a variety of problems. Some of the issues associated with copper deficiency include reduced disease resistance, wilting, reduced seed and fruit yields and an inability to flower. Young plant tissue growing in copper-deficient soil also shows signs of chlorosis, distortion and even death. When used in combination with regular soil testing, copper sulphate acts as a preventive deterrent to these problems.
The overapplication of copper sulphate in an area has a lasting negative impact on plants growing there. One of the potential negative effects of copper sulphate includes leaf discolouration, characterised by dark green leaves followed by white discolouration and resulting from induced iron chlorosis. The overuse of copper sulphate can also result in root damage, characterised by short, thick, stub-like growths of root. The root damage caused by the overapplication of copper sulphate can result in overall wilting, reduced growth or death of the plant.
Copper sulphate is a common ingredient in several fungicides used in gardens and fields. Copper sulphate-based fungicides are typically delivered as foliant sprays that are mixed with water and another chemical-hydrated lime or soda ash. These mixtures are commonly known as the Bordeaux and Burgundy mixtures. Used in this fashion, copper sulphate can act as a protective barrier against invasive fungi or a removal agent if used shortly after the initial fungal infection.