Assessing the extent and effects of herbicide drift into Danish hedgerows

Very low dosages of herbicides are known to cause effects on bird cherry (Prunus avium) and hawthorn (Crataegus monogyna). With the purpose of studying whether this is a general phenomenon two other common hedgerow species, Sambucus nigra (elder) and Sorbus intermedia (Swedish whitebeam), were exposed to a range of low herbicide dosages, and effects on leaves, flowers and berries were assessed. Furthermore, spraying was performed at field scale with a common tractor sprayer in five tracks parallel to a hawthorn hedgerow under varying weather conditions, in order to get realistic data for spray deposition in hedgerows, and the resulting herbicide effects on hawthorn fruit set were assessed. Elder was more sensitive to the herbicide than Swedish whitebeam, but the fruit set of both species was affected at herbicide deposition rates likely to occur at normal spraying procedures, as shown by the field scale experiments. The results may have implications for initiatives aiming at reducing herbicide effects on natural areas in the agricultural landscape.