It is important to use the right tool for the job. You wouldn’t use a hammer to tighten a screw. Herbicides can be considered tools as well, to help us perform task in the landscape.
As gardeners, it is very important to understand the groupings of herbicides in the garden. While herbicide may be a four-letter word to some, keep in mind a herbicide is simply a product used to kill a weed and can be an organic or a conventional product. Understanding which tool is right for the job is critical in achieving your end goals.
Herbicides can first be categorized into pre-emergent herbicides and post-emergent herbicides.
A pre-emergent herbicide, like the name implies, is one that takes effect on the plant before it emerges; typically not allowing the weed to get past the germination phase of growth. Preen, Amaze, and Dimension are but a few examples of a pre-emergent herbicide. The product must be applied before the weeds emerge, otherwise it will not have any effect. These are excellent products to use on a newly prepared bed and a lawn to help prevent weeds from occurring.
A post-emergent herbicide is one that takes effect on weeds after the germination phase. In other words, the weed is actively growing and needs to be removed. Post-emergent herbicides can be divided further into two categories. The distinction between the two is whether the herbicide kills weed indiscriminately – called nonselective herbicides – or if it kills certain weeds while not affecting others – called selective herbicides.
Nonselective herbicides, such as glyphosate and pelargonic acid (an organic option), will kill any weeds or other plant material they come in contact with. A selective herbicide is one that kills one type of plant while not harming another type. An example of a selective herbicide is 2,4-D. This product is often used in the lawn because it kills broadleaf weeds but does not harm grasses.
Understanding herbicides and how to use them properly and when to use them is very important in lawn and garden maintenance. Herbicides are tools we can use in the landscape. But not every tool is needed to get the job done, just as using herbicides may not always be the best approach to weed management in your lawn and garden.
There are many preventative ways to keep certain weeds out of your gardening areas. Mulching, mowing and my favorite product, “wrap around.” Wraparound is one of the best organic options in weed management: Wrap your hand around the weed and pull it. This may be a little tongue and cheek, but sometimes pulling weeds is easier and more cost-effective than mixing up a batch of a herbicide.
Assess your lawn and your garden this spring. Determine which weeds you have had in the past and which weeds you currently have. Then ask yourself: “Which tool is best to use at this time?” Should you use a hammer to tighten the nut or maybe just a crescent wrench?
The LSU AgCenter and the LSU College of Agriculture