A herbicide is a product used to kill unwanted plants. If the herbicides indiscriminately affects all plants it comes in contact with, it is considered a broad spectrum herbicide. Popular broad spectrum herbicides include products containing glyphosate, like RoundUp and Brush Be Gone. There are also acetic acid based broad spectrum herbicides, like Nature’s Glory Weed Killer and Burn Out.
Herbicides can also be selective and used to kill only targeted plants, for example, crabgrass killer.
A pre-emergent herbicide works by preventing seed from germinating, so they are more effective in controlling annual weeds. Preen is a popular pre-emergent herbicide for homeowner use.