The EPOP model: estimation of pesticide spray depostion and effects on terrestrial non-target plants

During the past years, the interest for semi-natural vegetation on edges immediately surrounding arable fields has increased significantly. These so-called field margins are part of the National Ecological Network in the Netherlands. Especially herbicides may have a large effect on such networks. These chemicals may alter biodiversity as a result of their effects on the plant species composition, diversity, development, growth or morphology. At this moment, issues like herbicide doses and allowable distances to field margins for spraying are being discussed. The EPOP model (Effects of Pesticides on Plants) combines downwind spray deposition curves from the IDEFICS- model with dose-response curves, resulting in a tool for estimation of the distances over which effects of herbicide spray drift in field margins are to be expected. Model results are interpreted in terms of quantitative effects on biomass, seed production and species composition. The model can be used as an extension of the tiered standard for risk assessment as proposed by EPPO.