Weed management in organic agriculture

Abstract

Even though public demand for organic products has increased in recent years all over Europe, concerns about potential increases in weed populations without the use of herbicides has limited the acceptance of organic farming practice. Despite the serious threat which weeds offer to the organic crop production, relatively little attention has so far been paid to research on weed management in organic agriculture, an issue that is often approached from a reductionists perspective. This paper aims to outline why and how this problem should be considered from a system perspective. Compared with the conventional agriculture, in organic agriculture the effects of different cultural practices (e.g. crop rotation, soil tillage, fertilization and direct weed control) on crop vs. weed relation usually manifest themselves more slowly. It follows that weed management strategy should be tackled in an extended time and needs to be fully integrated in a comprehensive cropping system rather than weed control per se. It is emphasized that physical weed control can only be successful where preventive and cultural measures (cropping system, mulching with cover crops, non-inverse soil tillage) are applied to reduce potential weed emergence and to improve crop competitive ability (crop pattern, intercropping, crop establishment) and to design direct control measures (cultivation and weed removal, physical and biological weed control methods). Emphasis is given to the necessity for a more flexible approach and fully integrated combination of the knowledge of weed biology, different cultural measures and direct weed control methods in order to maintain weed populations at threshold, or at least manageable levels. Introduction of a modern information technology could afford successful and easy flow of scientific and professional data targeting integrated weed management techniques. Furthermore, it will be possible to have adequate feedback, appropriate monitoring and control mechanisms. Permanent education and training process could be crucial in view of the fact that effective weed management in organic agriculture should include comprehensive and more sensible approaches, with a wide range of knowledge, skills and tools in the field of weed biology, as well as introduction of new weed control technologies.