Plant Talk |
CAUTION:The information and recommendations in this article are applicable to Harnett County, NC and may not apply in other areas.
WEED CONTROL IN LAWNS, 03/28/97
One definition of a weed is "a plant out of place". Thus, even a petunia could be a weed if it is growing in your carrot patch. For lawns, most people want a weed free patch of lush green vegetation. But judging by the amount of crabgrass, dandelions, and wild garlic/onion growing right now, that may seem impossible. Here are some helpful tips.
My first suggestions have nothing to do with pesticides. There are many other measures you can take to control weeds in your lawn. In fact, herbicides should be only a secondary line of defense.
The most important step is to make sure your lawn is healthy. A thick cover of grass will out compete many weeds for light, water, and nutrients. Be sure your lawn has the nutrients and pH level it needs for optimum growth (by taking a soil test, of course).
Also, take the time to repair those bare/patchy areas. A bare spot is an open invitation for weed seeds. Over the next few weeks would be a good time to replant those areas. Just remember the importance of soil preparation and caring for the new grass seedlings.
Mowing is another good tool, especially for cutting down weeds before they produce seed. A single plant may produce hundreds of seeds.
The non-chemical methods, however, will probably not give you a 100% weed-free lawn. If that is your goal, then herbicides may be necessary.
When using herbicides, as when using pesticides of any kind, be sure to read and follow all instructions that come with the product. This is important for your plants, your health, and the environment. Also check for precautions concerning newly planted grass.
It is also important to distinguish between broadleaf and grass weeds. Some examples of grass weeds are crabgrass, goosegrass, and foxtail. Examples of broadleaf weeds are dandelion, chickweed, creeping charlie, wild strawberry, and clover. Essentially, the "broadleaf" category includes most weeds that do not resemble grasses.
Now we are ready to look at chemicals. Crabgrass and other grass weeds are normally controlled with pre-emergent herbicides. This means the herbicide is applied before the weed seeds germinate. The germinating seedlings are killed as they come into contact with the herbicide. If you generally have trouble with crabgrass, now is the time to treat (by the time the dogwoods are in bloom).
Most broadleaf weeds, on the other hand, are controlled postemergent. We treat for them after the weeds have emerged. There are many broadleaf herbicides available for use in lawns, but a good bet would be one of the mixtures. These mixtures will control a wider variety of weeds. They normally contain chemicals such as 2,4-D, MCPP, dicamba, and MCPA, among others.
Wild garlic/onion is a special case. 2,4-D amine is the chemical of choice, but it must be applied carefully in centipede and St. Augustinegrass. These two grasses are easily damaged by 2,4-D, so the chemical must be carefully sprayed onto individual garlic clumps. The surrounding grass will die, but should grow back within a year.
If you have a specific weed that you would like identified, please call me for instructions on how to collect and send a sample.
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