Effects on hawthorn the year after simulated spray drift.

This paper describes the effect of a herbicide applied at levels consistent with off target movement on hawthorn the year following exposure. In the experiment, metsulfuron-methyl was applied in five dosages to individual trees in seven different hawthorn hedgerows. Spraying was conducted both at the bud stage and at the early flowering. Five endpoints (i.e. leaves, buds, flowers, green berries and mature berries) were sampled and counted. All were significantly reduced with increasing exposure. Present day risk assessment of effects on non-target plants is therefore likely to overlook significant effects on perennial non-target plants in the spray drift zone due to the focus on results from short-term laboratory test studies. The significance of the present study is underlined by the fact that the effects observed were significant, even though other influential factors such as herbivory and differential pollination were not eliminated and that experiments were conducted in multiple locations.