Herbicides

Any word that ends with ‘-cide’ means death to something. In the case of herbicides, it means death to some or all plants that it contacts.


Non-selective herbicides kill everything, while selective herbicides are slightly more choosy. Until the 20th century, weed management included cultural controls and old-fashioned elbow grease.

Man spraying herbicides in rice field (zefe wu) Pixabay

Chemical warfare

Chemical warfare research from WWII discovered how synthetic plant hormones and other chemicals could kill many broadleaf plants. Several chemical reactions are going on when these chemicals are applied. Some herbicides work by halting cell production in the meristems (growth tips). Other chemicals starve plants by interfering with the production of amino acids or by halting photosynthesis.

Using herbicides can lead to several problems, including:

• Overspray can kill nearby plants.
• An area may become unsuitable for planting for several years.
• Weeds become resistant (and we do not).
• Chemicals may enter groundwater, causing algae blooms and other environmental problems.
• Some herbicides may increase the risk of cancer. (Union of Concerned Scientists)
• Groundwater can become contaminated by herbicides.
• Forage grown for livestock may release herbicide residue through manure. (NC Cooperative Extension)

Loss of biodiversity is a serious problem when it comes to herbicides. Nature’s balancing act is delicate. The effects of this chemical use are not fully understood. For example, Roundup (glyphosate) has decimated global Monarch butterfly populations. Other herbicides, like Paraquat, are so dangerous that only licensed professionals are supposed to have access. Long-term exposure to paraquat can kill you. You can read more about the health effects of paraquat here.


Safer alternatives

While chemical herbicides offer short-term convenience, there are many safer, sustainable options, including the following:

• Hand weeding
• Maintain healthy plants
• Mulching
• Good garden design
• Proper irrigation methods
• Install porous grout in hard surface cracks or apply clove or lemongrass oil.

If you must apply chemicals in the garden, follow the package directions exactly. Confirm it is the correct herbicide for the site and the specific weeds. Apply too much, and the excess enters our water supply. You will also want to ensure that the weeds are in the correct life stage for the herbicide to be effective. If a chemical claims to be pre-emergent, it will attack germinating seeds. Post-emergent herbicides attack growing plants, and they work better on young plants. Post-emergent herbicides can be foliar (leaf absorption), root, contact, or systemic. Systemic herbicides are absorbed and spread throughout the plant.


Be sure to read and follow product labels carefully. And dispose of the container properly. Better yet, practice sustainable, organic gardening.