The Herbicides For a Cactus

Glyphosate

• Glyphosate is the active weed-killing ingredient in several commercial brands commonly sold at garden centers and nurseries. Look for brands including Roundup, Eazy Weeder, Zero and Tumbleweed to name a few. Glyphosate weed killers are categorized as "non-selective" herbicides. Glyphosate-based herbicides do not discriminate. They kill everything. As a result, you need to be careful about where you spray it. Follow the instructions carefully and only spray the weed -- not the cactus.

2,4-D

• Another highly effective chemical used in weed killers is 2,4-D. It's the active Ingredient found in trade-name brands that include Weedone, Barrage, Plantgard and Savage. The Environmental Protection Agency (EPA) gives 2,4-D a GUP status, meaning it is approved as a "General Use Pesticide" in the United States. It is a selective "systemic" product that penetrates the soil in search of the roots of the broadleaf weeds. Unlike non-selective weed killers, 2,4-D only goes for weeds. Once the 2,4-D active ingredient makes contact with the roots, it suffocates the roots, and therefore stops the the weed from growing. Products with 2,4-D are sold in powder, liquid and water-soluble forms.

Hexazinone

• Hexazinone is the active chemical ingredient in products such as Pronone and Velpar. Hexazinone is sometimes used in combination with other herbicides such as bromacil and diuron. Like all chemical-based weed killers, hexazinone is toxic and containers bear caution and poison labels. Hexazinone is also a selective systemic weed killer, inhibiting the photosynthesis process from developing, and thus retarding the growth of the weed so that it dies. Hexazinone is sold in powder, granular and water-soluble concentrate forms.

Metsulfuron-Methyl

• An herbicide that works as both a pre- and post-emergent is a good choice. You can treat a new cactus planting bed before you set in your plants and, if you spot weeds later in the growing season, you can stop them dead in their tracks. That's what weed killers that contain metsulfuron-methyl will do. Brands on the market include Ally, Allie, Gropper and Escort. Like 2,4-D and hexazinone -- metsulfuron is a systemic selective herbicide. Once it sinks into the soil, it doesn't take long for it to target the roots of the weeds and putting their weed life to a welcomed end. Replenish the soil with new soil after weeds have been eradicated by herbicides -- especially if you plan on putting new plants in the spot that you treated. Herbicides can leave residual ingredients that might target and kill new plantings placed in formerly treated areas.