The effect of site preparation on the establishment of a perennial wildflower and a prairie mixture was compared on five highway rights-of-way in southwestern, central, and northern Ontario. The site preparation treatments of the existing perennial cover were: 1) control, 2) broadcast glyphosate herbicide application, or 3) broadcast glyphosate herbicide application plus cultivation. The sites were mown prior to drill seeding. The experiments were planted in 1990 and 1992 and evaluated for total cover, cover of seeded species, and noxious weeds. The wildflower mixture established more rapidly than the prairie mixture. The wildflower seed mixture established better with either site preparation treatment compared to the control regardless of the type of vegetation present prior to planting. By 3 years after treatment the original vegetation had reinvaded to a greater degree with the herbicide treatment, indicating that the herbicide plus cultivation provided better control of the original perennial cover. Four years after seeding, neither seed mixture had established in the control, indicating that control of perennial vegetation was crucial for establishment of these seed mixtures on existing sites.
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