Environmental Risks of Fungicides Used in Horticultural Production Systems

Abstract

Fungicides are widely used in horticultural production systems to ensure crop quality and production. However, the use of such fungicides may cause adverse effects to terrestrial and aquatic ecosystems if fungicide residues persist in soil, or if they migrate off-site to surface and ground waters. Whilst a great deal is known about the fate, behaviour and toxicity of Cu in both terrestrial and aquatic environments, comparatively little information has been reported for the synthetic organic fungicide compounds. The accumulation of Cu in surface soils following the use of copper fungicides has been reported in many regions of the world, and there is evidence suggesting adverse effects to earthworms and soil micro-organisms. However, only a small number of studies have measured the persistence of synthetic organic fungicide compounds in the soils of horticultural properties, providing a limited knowledge base on which to assess the likely risks. Similarly, only a few studies have sought to investigate the off-site movement of fungicides and their presence in aquatic environments. Assessments of the behaviour and toxicity of fungicides in the environment are complicated by the environmental and biological availability, which varies greatly across different soils, sediment, and waters (i.e. large influence of pH, clay, organic matter). Using ecological risk assessment principles, it is currently not possible to characterise the environmental risks of fungicides with any degree of certainty. An exception being risks of Cu accumulation to soil organisms, but, even here there is a high degree of uncertainty due to large variability in ecotoxicological effect values across different soil types. The relative risks of different fungicides needs to be considered when making recommendations on the future management of fungicide use. Current