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.


Herbicides are chemical weed killers. Non-selective herbicides kill everything, while selective herbicides are, well, selective. Until the 20th century, cultural controls and good old fashioned elbow grease were used to rid an area of weeds.

Man spraying herbicides in rice field (zefe wu) Pixabay

Chemical warfare

Chemical warfare research from WWII determined that synthetic plant hormones and other chemicals could be used to kill many broadleaf plants. There are several chemical reactions going on when these chemicals are applied. Some grass 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:

• 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)
• forage grown for livestock may be released through manure (NC Cooperative Extension)

Loss of biodiversity is another serious problem. Nature’s balancing act is delicate and the full effects of chemical use is not completely understood at this time. For example, Roundup (glyphosate) has decimated global Monarch butterfly populations and increased the use of pesticides that end up in our food and water.


Safer alternatives:

• hand weeding
• maintain healthy plants
• mulching
• good garden design
• proper irrigation methods
• install porous grout in cracks or apply clove or lemongrass oil

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


Be sure to read product labels carefully and completely, and dispose of the container properly.