Weed Control In the Landscape

Weeds can be characterized as selected vegetation that is undesired within other vegetation that is selectively desired. The operative term is selectively desired. Fortunately there are chemical herbicides (weed killers) that are selective in the types of weeds that they kill or affect.

In general, there are four types of selective Herbicides:

1. Grass Killers

These chemicals kill grasses and do not harm most foliage of plants with leaves on them. This chemical can be used directly over many types of plants and groundcovers to kill grasses. Fortunately, for those of us in the south, this chemical works well on Bermuda Grass.

Read the label carefully to determine which plants it can be used on. If you have a leaf plant that is not listed on the label it is likely because it has merely not been tested on that leafy species. You may wish to try it over one plant before applying it over many of the same that you have in your garden.

These products are primarily commercially available. There are two different ones available: Fuslaid or Post. These are spray-on chemicals that mix with water to apply to grass weeds that are growing in ornamental planter beds.

Caution: Follow application directions and rates carefully. Typically they take about 2 weeks (from time of application) to take effect.

2. Broad Leaf Weed Killers for Use In Lawns

These chemicals are the opposite of the Grass Killers. They can be applied directly over most lawns and will selectively kill the broad leaf weeds without harm to the lawn. These chemicals are very volatile and while relatively safe for humans, drift will severely damage adjacent plantings. Spray on calm days with low pressure to reduce spray drift.

Hi-Yield Lawn Weed Killer and Weed B Gone are two popular effective broad leaf weed killers for lawns that are available on the retail market. There is, however, a newer product called Turflon that is a broad leaf killer that is not registered for use on lawns of Bermuda or St. Augustine because it will severely damage or kill those species of grasses. This product is not yet labeled as a Bermuda Grass killer in grass lawns, however, since this particular broad leaf killer will not harm most desirable turf grasses (Blue, Rye and Fescue) it will damage or kill Bermuda, and it has been used to control Bermuda Grass within fine turf grass lawns.

Do not use these products on shrubs or ground covers that have leaves, and that you wish to keep.

Turflon is a spray on chemical that mixes with water to apply to lawns in order to kill weeds. Follow application rates and directions carefully, including ambient temperature restrictions.

3. Broad Spectrum Non-Selective Herbicides

The non selective herbicides are self explanatory in that they are not selective as to what they kill. They generally do damage or kill virtually any plant material they contact. Killzall or Round-up fit into this category.

To avoid drift onto desirable plants or grasses, make sure to spray non-selective herbicides such as Killzall or Roundup when there is little or no wind. Adjust the tip of your sprayer to spray more of a concentrated stream than a fog to reduce drift.

Killzall or Roundup can be used anywhere to kill almost any type of weed or grass and are especially good for sidewalk cracks and areas with no desired plantings.

Avoid spraying these products near ponds, lakes or other bodies of water as injury may ocuur to fish and other aquatic life.

4. Seed Killers

The fourth type of selective herbicide is that of a pre emergent weed killer, or a seed killer, that will kill seeds but will not harm existing plants or lawns depending on the label.

Landscape Beds or Islands:

A product called Treflan is a granular product that will not harm almost any commonly used plants. This product is best applied with a whirlybird spreader. We use Treflan to as a pre-emergent weed control in landscape beds which contain shrub and tree or annual flower plantings. Do not use this product where you plan to plant grass seed, wildflower seed or any other type of desirable seed as it may inhibit germination. We apply Treflan once per year in January or February to gain control of weeds by killing seeds before they have a chance to germinate in spring.

Lawns:

A product called Team 2G is a granular product that will kill weed seeds in lawns without harm to the grass. In Zone 8 of Georgia we apply this product to lawns in mid-February to control crabgrass and various other weeds by killing the seeds before they germinate. A fall application is suggested to control poa annua and various other winter weeds.

Caution: Always read the label as some Pre Emergent herbicides may harm some plantings especially herbaceous type plants such as annuals.

Chemical Application

Chemical labels have the signal word CAUTION, WARNING, or DANGER! indicate the relative hazard of the products. The CAUTION word is the least hazardous to humans, while the DANGER signal word is the most hazardous to humans. This is true for all chemical products, including those around the household.

Whenever applying any of these chemicals, especially as an amateur, you should protect yourself against the concentrate and the mixed product. While these products are safer in their diluted rates after mixing with water and also after drying in the garden, do not underestimate the safety required to apply these commercial chemicals. Their chemicals are concentrated and at their best prior to mixing with water. Therefore, before opening or handling any open container or bag, utilize goggles, rubber gloves, and long sleeves. A dust mask is suggested..

Pre-read the label as it is and it will dictate the precautions!

Along with the specified safety equipment, the equipment required to apply the granular herbicide would include a broadcast spreader such as a hand-held whirly bird type. The liquid chemicals would be best applied through 1 to 3 gallon pump sprayers. It is recommended to have different sprayers for the different chemicals. Since spot spraying may be necessary from time to time, it may be useful to label the sprayers with a felt pen and store unused diluted portions for subsequent use within the containers.

If you plan to use the same sprayer for various chemical applications make sure to clean the sprayer before switching to another product. Fill sprayer with halfway with clean water, shake well and then spray out to clean tank, hose and nozzle before switching to another chemical.

Do not rinse containers into storm drains or sewers.

Also there are colorants that can be purchased to add to the chemical solutions so that you can easily see the area and amounts that have been sprayed. The spray colorants are inexpensive, and dissipate in the sunlight within a few days. Some colorants will form a gel if left in sprayer. Make sure to empty and clean sprayer after use of colorants.

For more information on weed control in the landscape visit the Weed Control Page at WilsonBrosOnline.com