ABSTRACT
Managing weeds in organic farming systems requires a broad, systems perspective, with consideration of operations that can stress weeds at multiple points in their life histories. Simply substituting cultivation for herbicides is generally inadequate. Compared to most herbicides, cultivation efficacy is usually lower and more variable. Repeated cultivation is a simple, but inefficient solution to this problem, and many successful organic farmers rely on a large suite of management tactics beyond cultivation. The foundational principles of reducing weed density and the damage caused by surviving weeds remain the same, but tactics are deployed strategically to reduce the seed and/or propagule bank in the soil. Physical weed control remains a key practice in many crops, but this seedling-focused tactic is generally supported by a suite of ecologically based practices chosen for multiple benefits. Our experience suggests that successful farmers may use widely differing strategies to address their weed problems. Some simply substitute repeated cultivation for the herbicides that would otherwise reduce weed density. Others support cultivation with one or more strategies to improve crop-weed competitive relationships, or rely on intensive mulching to preempt weed establishment all together. At the highest level of management, farmers exploit ecologically based strategies using diverse cropping and disturbance regimes. Here, weeds are managed in the context of soil-improving management, diverse enterprises, and minimal reliance on purchased inputs ¬– in short, the foundations of sustainable agroecosystems.
