Development of Alternative Weed Management Strategies

Abstract

Concerns in the public and agricultural sectors about agricultural practices have led many weed scientists and producers to consider alternative weed management strategies. Weed management practices have been influenced greatly by the availability of selective herbicides for major crops. The impact of herbicides has been so dominating that weed science is often perceived to be the science of herbicides rather than the science of weeds. The general public and many agricultural producers are searching for alternatives to herbicide-intensive weed management practices. A shift away from dependence on herbicides is complicated by a poor understanding of weed biology and ecology and the availability of few alternative weed control tactics. Education and research efforts have to focus on the application of existing knowledge as well as the development of new fundamental knowledge. Reductions in herbicide use can be attained within the framework of existing management systems. However, given the poor understanding of weeds and lack of control options, new approaches to weed management are needed. Weed scientists have to play a central role in the development of new cropping systems to avoid continuation of reactive approaches to weed control. Research Question Concerns over current practices have lead many weed scientists and crop producers to seek alternative strategies for weed control. The goal of these strategies is to develop systems that provide producers with more options for weed control and reduce dependence on tillage and herbicides, thus minimizing the environmental, biological, economic, and societal impacts of controlling weeds. Herbicides have been a valuable tool and have provided benefits to the farm and urban communities. However, weed control has to be viewed as a more integrated science. Refocusing away from overdependance on a single technology (herbicides) will require greater understanding of biological systems than we currently possess. Literature Summary Weed management is in transition from strict reliance on control of existing problems to placing greater emphasis on prevention of propagule production, reduction of weed emergence in a crop, and minimizing weed competition with the crop. Weed management emphasizes integration of techniques to manage or anticipate problems rather than solving them after they are present. Weed management does not eliminate the need for control nor does it advocate that our best control techniques be abandoned. Its goal is to maximize crop production where appropriate and optimize grower profit by integrating preventative techniques, scientific knowledge, and management skills. Weed control is achieved by physical, chemical, or biological disturbance. All forms of disturbance exert selection pressure and result in the survival and proliferation of the best adapted plants. Several decades of use of modem production practices have not eliminated weeds, but have greatly changed the population dynamics of weed communities. In order to develop new cropping and weed management systems, the impacts of agricultural practices on weeds must be better understood and anticipated. Applied Questions Are there practices that growers can implement immediately to reduce herbicide use? Yes. The use of mechanical control operations alone or in combination with herbicide banded over the crop row or reduced rates of herbicide can reduce herbicide use and maintain weed control. Field scouting and record keeping may also lead to more efficient use of herbicides. Weed thresholds and decision aid models may also lead to reduced use. What type of research is needed to develop alternative weed management systems that go beyond current cropping systems? A better understanding of weed biology and ecology is the key. This information will aid in the development of site-specific management systems and in the redesign of cropping systems. There is also potential for new control practices such as biological control, allelopathic plants, smother plant systems, or more competitive crop cultivars.