A pesticide is a chemical that controls pests (e.g. caterpillars). What you mean is a herbicide that kills plants. In your case something that kills grasses (monocots) and not broad leaf (dicots). It is more common to find people killing broad leaf plants in grasses, such as lawns.

But Ravi is correct in his comment. You need to pose a more specific question- you cannot ask for general help on PlantVillage.