Purchase an herbicide that contains picloram to treat and kill goldenrod. Use a pump-up sprayer or backpack sprayer to treat goldenrod that is scattered throughout the pasture or for the treatment of a small number of plants.
Follow the manufacturer's instruction to properly mix the herbicide to the correct proportion in the pump-up sprayer. As an example, a 1-percent solution of herbicide containing picloram is typically added to a half-tank of water before completing the fill-up of the tank.
Add a spray-marking dye to the herbicide mixture. This dye is typically blue in color and marks the plants that have been sprayed.
Spray each individual goldenrod plant with the herbicide. Wet each plant thoroughly until the goldenrod is saturated, but not to the point where the herbicide drips.
Allow one growing season to pass before mowing the area. Do not disturb the plants or try to remove them during this time.
Things You Will Need
- Pump-up garden sprayer
- Backpack sprayer (optional)
- Spray-marking dye
- A boomless broadcast sprayer may be needed for areas heavily infested with goldenrod. Consult a dealer at your local tractor supply store for information and instructions about the use of herbicides with boomless broadcast sprayers.