Towards understanding the soil and water fate of pesticides in South African plantation forests
The presentation will present results of a trial that investigated the environmental fate of pesticides applied operationally in South African plantation forests
Pests and diseases cause significant wood volume losses in plantation forests globally. Pesticide-use within plantations is an important component within any broader Integrated Pest Management Programme. Responsible pesticide-use however, is imperative as pesticides may move from the site of application and adversely affect surface and ground water quality, human health, and aquatic and terrestrial environments. An understanding of the fate of pesticides, following application, is the first step towards responsible pesticide-use. A trial was therefore implemented on a site representative of plantation forestry areas in South Africa (SA) to investigate the soil and water fate of pesticides operationally used, under SA forestry silvicultural regimes and environmental conditions. The results indicate that pesticide concentrations in water are highest following the first rainfall after application. From the 18-water sampling events, glyphosate was detected once, metazachlor twice, triclopyr four times, while cypermethrin and azoxystrobin were consistently below the detection limit (<0.01 µg L-1). Compared to water, pesticides persisted longer in sediment and soil. Metazachlor and cypermethrin were detected in soils and sediment even after 6 months post-application. The next step towards responsible pesticide-use would be to link the pesticide concentrations obtained in water, soil and sediment to pesticide ecotoxicity endpoint studies.