Current use of copper, mineral oils and sulphur for plant protection in organic horticultural crops across 10 European countries

Abstract

The use of several plant protection inputs of mineral origin, such as copper, sulphur or mineral oils is seen as contentious by many consumers and stakeholders within the organic sector. Although the use of these inputs is legal in organic systems and also applied in non-organic agriculture, their use by organic growers raises questions for organic practice, which aspires to be free from toxic, non-renewable chemicals. Data on the current use of permitted plant protection inputs is currently scarce, especially in horticulture where chemical inputs deserve special attention since horticultural products are often readily edible. A mapping of the use of copper, sulphur and mineral oils was conducted by collecting expert knowledge across 10 European countries during May–October 2018, i.e. before the limitation of copper use to 4 kg ha⁻¹ year⁻¹ from February 1, 2019. Results show that copper is widely used by Mediterranean organic growers in citrus, olive, tomato and potato production. The annual limit of 6 kg ha⁻¹ year⁻¹ was not always respected. We also found that tomato producers apply high amounts of copper in winter crops in greenhouses. Mineral oils are applied to control scales, mites and whiteflies. Sulphur is also commonly used by organic vegetable growers, especially in greenhouses. We conclude that the high usage found in various different crops (especially Mediterranean crops) confirms the need for researching alternatives.