ABSTRACT
Integrated pest management (IPM) for weeds is considered to be in the early stages of development, especially when compared with insect and disease management. The need to develop IPM principles for weed management will increase as weed population shifts, species adaptation, and environmental impacts of weed control methods threaten the sustainability of agricultural systems. In this paper, we propose a framework for discussion and development of the weed component of IPM. We describe five levels of weed IPM that encompass progressively larger spatial scales and longer time periods, with corresponding changes in goals and complexity of supporting technology and information. The first level consists of the use of a 240single weed management tool at the field level, such as the use of a herbicide as the sole means for weed control. Level II integration incorporates tactical use of multiple tools for weed management, including combinations of herbicides, crop rotation, and mechanical and biological controls, as well as other cultural practices designed to reduce the damage caused by weeds. Level III represents the threshold of much current weed science research, and involves the design of entire cropping systems at the farm and landscape level as a strategy to resist weed invasion, tolerate weed presence, and decrease weed population survival and persistence. Levels IV and V are more speculative because the ecological basis for them is in development. Level IV addresses the management of habitats and landscapes at the ecosystem level to address large scale problems related to weed spread, dispersal, and invasion. At Level V, national trade and environmental policies are considered with respect to their impact on weed populations at a global scale. Approaches that might be taken at the various levels to management of herbicide resistance are described. Research has tended to focus on the first two levels of integration; however, development of IPM principles for weeds will require that attention be given to all levels of integration so that agricultural systems can be designed to more effectively deter and withstand the inevitable presence of weeds. [Article copies available for a fee from The Haworth Document Delivery Service: 1-800-342-9678. E-mail address: getinfo@haworthpressinc.com]
