Monday, 7 November 2005
7

Mechanical Weed Management in Conservation Tillage Systems.

Suzanne Kopan and Robert S. Gallagher. Washington State University, Department of Crop and Soil Sciences, 201 Johnson Hall, Pullman, WA 99164-6420

Soils in much of the Pacific Northwest are highly prone to wind and water erosion under conventional farming practices. Conservation tillage systems help mitigate these effects but tend to favor the development of certain soil-borne fungal pathogens (i.e. Rhizoctonia spp., Pythium spp., and Fusarium spp.) and depend on herbicides for weed control, leading to the development of herbicide resistant weed populations. This project evaluated a Phoenix® rotary harrow prototype and a high-residue rotary hoe for mechanical weed control in conservation tillage wheat (Triticum aestivum) and dry pea (Pisum sativum) production systems. We hypothesized that a pre-plant rotary harrow operation coupled with multiple rotary hoe operations could provide non-selective control of weeds, reduce soil-borne diseases, and help deplete soil weed seed bank populations. In addition, the rotary harrow and hoe could provide minimal soil disturbance within the top 5 cm of soil while leaving a majority of the crop residues on the soil surface to protect against erosion. Preliminary data suggested that problem weeds, such as prickly lettuce (Lactuca scariola) and wild oat (Avena fatua), could be controlled in wheat by this integrated mechanical approach without causing reductions in crop stands. Mechanical management of these weeds in spring peas appeared to be more problematic.

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