ARABLE FLORA IN SPRAYED AND UNSPRAYED CROP EDGES

On 15 conventionally managed arable farms in an intensive arable farmi ng district on marine clay in the Netherlands, edges of winter wheat, sugar beet and potato crops were either sprayed or unsprayed with herb icides and insecticides, during the period 1990-1994. The presence (fr equency) and abundance (ground cover) of farmland plant species within sprayed and unsprayed edges and in the sprayed field centre were comp ared. In all three crops, leaving 3-6 m wide edges unsprayed, both the presence and abundance of farmland plants increased, by factors of 4. 8-12.1 and 1.5-2.7, respectively. The effect was greatest in the winte r wheat crop. The increase was attributable mainly to dicotyledonous s pecies. Although the majority of the plants were common farmland speci es, there was a major enhancement of the floristic value of the unspra yed fields. In the sprayed centres of the fields, the presence and abu ndance of farmland plants as well as the overall floristic value were consistently lower than in the sprayed and unsprayed edges. Leaving th e crop edges unsprayed significantly decreased crop cover in sugar bee t fields only. If compatibility with farm management is also taken int o account, the measures investigated appear to have the greatest poten tial in winter wheat. (C) 1997 Elsevier Science B.V.