Understanding the Chemicals in Common Weed Killers

Although dozens of brand-name weed killers line store shelves, they rely on only about five active chemical ingredients. Most are classified as broadleaf herbicides, targeting plants with large foliage while typically sparing grass. Some formulations add extra ingredients to kill grass as well. The label lists the chemical name first, followed by a trade name; the first one or two ingredients are the primary active agents, while the rest are often inert fillers.

Key Active Ingredients

2,4-Dichlorophenoxyacetic Acid (2,4-D)

Found in products like Scotts Green Sweep, Ortho Weed B Gon, and Triplex. These "weed and feed" formulas kill broadleaf weeds while fertilizing grass. This chemical is a surface and groundwater contaminant and may affect the human endocrine system.

Dicamba (2-Methoxy-3,6-dichlorobenzoic acid)

Used in UltraStop Lawn Weed Killer, Scotts Pro-Turf, and Tracker. Also a broadleaf herbicide, the EPA flags it as a potential toxin, and studies link it to non-Hodgkin's lymphoma.

Mecoprop (MCPP) (2-Methyl-4-chlorphenoxy-propionic acid)

Present in Menards Premium Weed & Feed, Mecomin-D, and Kilprop. The International Agency for Research on Cancer classifies it as a possible human carcinogen, and it harms birds.

MCPA (2-Methyl-4-chlorphenoxyacetic acid)

A component of Agritox, Envoy, and Vacate. Often combined with MCPP for added potency. Listed as a possible carcinogen and a groundwater contaminant.

Glyphosate (N-phosphonomethyl glycine)

Major ingredient in Ortho Ground Clear, Ranger, and Pondmaster. A broad-spectrum herbicide that kills grass and other plants. It leaches into groundwater and is toxic to aquatic life.

All these chemicals effectively kill weeds but must be applied strictly according to label instructions to avoid collateral damage to desirable plants and the environment.

Learn more about broadleaf weed killers and find additional resources at our weed killer information site.