Copper pesticide

A copper pesticide is a copper compound used as a pesticide or fungicide. In the UK the Soil Association (one of the organic certification authorities) permits farmers to use some copper fungicides on organic land used for the production of certified organic crops only if there is a major threat to crops.^[1] During the 2008 growing season the compounds were applied to much of the organic potato crop to control potato blight (Phytophthora infestans).^[2] The compounds permitted are copper sulfate, copper hydroxide, cuprous oxide, copper oxychloride, copper ammonium carbonate (at a maximum concentration of 25 g/l), and copper octanoate. According to the Soil Association the total copper that can be applied to organic land is 6kg/ha/year.^[3] This limit is designed so that the amount of copper in the soil does not exceed the limits specified in the Soil Association standards for heavy metals. Such copper compounds can build up in the soil and in excessive concentrations cause liver, kidney and blood disease.^[4]

Notes

1. Section 4.11.11, Soil Association Organic Standards for Producer, Version 16.1, April, 2010
2. "Thousands of tons of organic food produced using toxic chemicals" article by David Derbyshire in The Daily Mail 1 January 2008
3. Links to forms permitting application of copper fungicide on the website of the Soil Association
4. "Thousands of tons of organic food produced using toxic chemicals" article by David Derbyshire in The Daily Mail 1 January 2008