Prospects for combining biological weed control with integrated crop production systems, and with sensitive management of alpine pastures in Switzerland

Normally, a broad spectrum of weeds has to be controlled in arable crops. W hen applying ecologically sound cropping techniques, such as cropping syste ms with living mulch (e. g., in maize), or control strategies with specific timing of phytosanitary interventions to favour natural antagonists (e. g. , with late weed control to favour predators of aphids in sugar beets), mos t of the weed species can be controlled effectively. However, some weeds, s uch as the bindweeds Convolvulus ni arvensis L. and Calystegia sepium (L.) R. Br. or late emerging Amaranthus species, need supplementary control meas ures. In these cases, biological weed control, which generally aims at the control of a single weed species, may be suitable to complement. such ecolo gically sound cropping techniques. In pastures, especially of alpine region s, generally only single weed species need to be controlled. This must be d one without reducing the species richness of the flora and, thus, high sele ctivity is required. Socio-economic projections suggest that livestock may be withdrawn from the less productive, bur high conservation value, margina l grassland, which in turn would exacerbate weed problems. The use of herbi cides, even when possible, disagrees with public opinion. Biological contro l can be the appropriate means of control both to support sustainable pastu re management and to conserve biodiversity of these habitats.