Weed Management for Organic Crops

Abstract

Weed management in organic vegetable production systems must involve the use of many techniques and strategies, all with the goal of achieving economically acceptable weed control and crop yields. Weeds can always be pulled or cut, but the question is simply how much time and money can a grower expend to reduce weed pressure. The more a grower is able to reduce weed pressure, the more economical it is to produce crops. Ideally, growers would like to achieve a level of zero weeds on the farm. In practice, this may not be achievable, but any reduction in weeds and in the amount of weed seed or perennial propagules reaching the soil will make subsequent weed control operations less expensive. An understanding of what resources weeds require and why weeds are present in the first place is useful when you begin to formulate a control strategy. For weeds to grow, they must have access to water, nutrients, and light. The first or biggest plant to occupy a site has a competitive advantage over later plants. The cultural practices used in vegetable production (for instance, using transplants, pre-emergent flaming of weeds, pre-germination of weeds) often provide opportunities for the crop to gain that advantage. The goal is for the crop to out-compete the weeds, reducing the availability of resources to the weeds. If you can give the crop a competitive advantage through organically acceptable techniques, subsequent hand weeding operations and costs can be minimized. The following are common techniques available to organic growers to manage weeds in vegetable production operations.