ABSTRACT
Weeds have always plagued farmers. In an ecological sense, most weeds are plant species that have evolved to occupy resource niches left open by disturbance and lack of species diversity. Because most agriculture production systems are characterized by species-poor crop monocultures and some degree of soil disturbance, these systems present an open door to weedy species. Since the advent of herbicide technology in the 1940s, weed management has become increasingly reliant on synthetic chemicals. However, in spite of the undeniable success of herbicides, weeds remain problematic for all crop production systems. Continued evolution of herbicide-resistant weeds, and concerns about human health and environmental effects of synthetic chemical herbicides, have led to a resurgence of interest in non-chemical weed management tactics. The enormous recent growth of the organic food industry has also spurred renewed focus on the need to reduce effects of weedy plants without using synthetic herbicides. Organic crop production systems present unique and difficult weed management challenges, because organic farmers cannot use synthetic herbicides. Because of these challenges, organic farmers typically acknowledge that weed management is a top concern. Furthermore, weed problems may deter some farmers from transitioning to organic, or may drive producers who have transitioned back to conventional approaches. Because consumer demand for organically produced food is strong and continues to increase, weed management challenges in organic systems must be solved to ensure that farmers can continue to meet this demand. Additionally, escalating problems with herbicide-resistant weeds will increase the need for non-chemical weed management approaches, even in conventional production systems currently dominated by chemical weed management.
