Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/1995
Publication Date: N/A
Citation: Interpretive Summary: Reduced profits and the lack of effective integrated weed management programs have limited the adoption of minimum and no-till planting systems for wheat in the Pacific Northwest (PNW). In the Palouse Region of the PNW, over 80% of the best agricultural land is highly erodible and conservation tillage is the most effective and economical means of controlling soil erosion. Winter annual grass weeds such as downy brome cannot be controlled selectively with herbicides in the growing crop, therefore producers rely on moldboard plowing to control winter and spring annual grass weeds. A 9-yr interdisciplinary, integrated weed/pest management project developed and refined a conservation cropping system for wheat in the PNW. This system utilized a 3-yr crop rotation and a combination of no-till and minimum tillage systems. The system effectively controlled weeds, especially downy brome, reduced erosion potential by 90%, ,and was less economically risky and more profitable than traditional farming systems. Impact of this successful conservation IPM cropping system has been recognized at the local, regional, and national levels. Project information and data have been used by local bank officials to evaluate riskiness and profitability of cropping systems, by regional Natural Resource Conservation Service to develop farm compliance plans, and by the National Association of Wheat Growers to develop strategies for pesticide use and reduction and IPM farm policies.
Technical Abstract: In 1985, a 9-yr integrated pest management (IPM) study was initiated to develop and refine profitable conservation cropping systems in the Palouse wheat region of the Pacific Northwest. Weed scientists from the USDA-ARS and land-grant universities led a team of researchers and extension personnel from eight disciplines to investigate the interactions of crop systems, tillage systems, and weed management levels on crop production. Ineffective weed control has been a major deterrent to the adoption of conservation tillage by wheat growers. With this in mind, the primary focus of the scientists on the IPM project was integrated weed management in conservation crop production systems for highly erodible land. For the first time in the Pacific Northwest, systems research developed a conservation production system using a 3-yr crop rotation that effectively controlled weeds, reduced erosion, was less risky than traditional farming systems and was profitable. Broadleaf weeds were more prevalent in the 3- yr rotation of winter wheat-spring barley-spring pea compared to continuous wheat in both conservation and conventional tillage systems. In conservation tillage, troublesome grass weeds included wild oat and downy brome. Wild oat was controlled effectively at the moderate and maximum weed management levels under conservation tillage in the 3-yr rotation. Two years out of winter wheat (3-yr rotation) reduced greatly downy brome populations. In contrast, growing a spring crop 1 yr, followed by 2 yrs of winter wheat was not effective for controlling downy brome. Effective weed control was instrumental in developing successful conservation IPM cropping systems, and education and technology transfer were important in helping action agencies assist growers in adopting these systems.