Exotic annual weeds have transformed western North America, particularly in sagebrush-steppe systems. Restoration of these invaded sites has been met with low levels of success. Pre-emergent herbicide provides a means to control annual weeds, but typically, this treatment does not allow for the concurrent seeding of desired species. Seeding within a deep, U-shaped furrow following herbicide application may be a method to reduce pre-emergent herbicide effects by transferring the herbicide away from the seed at the time of planting. We tested this potential planting technique by spraying plots with or without the pre-emergent herbicide imazapic, and planting bunchgrass seeds either with or without a deep furrow. Treatments (i.e. spraying and furrowing) were applied using mechanical equipment within a single pass, at six sites. In plots without imazapic, we found that deep furrows generally had higher seedling emergence, density of juvenile plants, and above-ground biomass when compared to no furrows. For plots with imazapic, deep furrows also generally improved measured plant metrics for the seeded species compared to plots without furrows. For example, the density of juvenile plants in deep furrows ranged, by study site, between 62% – 97% and 41% – 89% higher than the no furrow treatment, for plots with and without imazapic, respectively. Plots with imazapic and deep furrows was not always as effective as plots without imazapic and deep furrows. Deep furrows also reduced exotic annual weeds in the first year after planting, but weed reduction was generally more effective when this treatment was applied with imazapic. Overall, this research provides evidence that in most instances, the use of deep furrows alone is sufficient to improve seeding success. However, in areas with high weed cover, the application of herbicide followed by the creation of deep furrows in a one-pass system should be considered.



College and Department

Life Sciences; Plant and Wildlife Sciences



Date Submitted


Document Type





furrow, imazapic, invasion, restoration, cheatgrass



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Life Sciences Commons