Weed Control


What to do this week –By Mark Govan, Host “Florida Gardening”

ABC Pest Control Inc. FloridaDuring the winter months our lawns go into a slow growth mode or depending on how cold the temperatures are they may go into complete dormancy. For those of us who cut our own lawns this is a relief. We do not have to get the lawn mower out of the garage every week or sometimes twice a week to perform our ritual mowing of the turf grass. Some of us can even wait three to four weeks between mowing. Warm season turf grasses such as Bahia, St. Augustine, and Zoysia slow their rate of growth during our winters because of several factors. Reduced daylight hours, cold nights and limited rainfall all contribute to this period of dormancy. Even though the foliage you see on top is not growing or is turning brown, there is some good news. The roots continue to grow during this period to prepare the grass for the warmer weather ahead. Unfortunately, with the absence of lush green foliage covering our soil, weeds begin to show up in mass.
Weeds need light to germinate and during our summer months the weed seeds which line the surface of the soil are shaded by the grass which is actively growing. Most weed seeds have a tough time germinating when you have a healthy stand of grass. Although a healthy lawn helps to prevent weeds from growing, this is not an absolute and many lawns even if they are growing and healthy are infested with at least a few weeds. Your lawn can also get weeds if your grass has thin areas or areas that are shaded during the day leaving openings for weeds to grow through. One thing to keep in mind is that there is a half a ton of weed seeds for every acre of ground in the world so weed pressure is always with us waiting for an opening.
Winter brings this weed pressure to a whole new level. Certain weeds called winter annuals are broadleaf weeds that grow primarily in the cooler months when conditions are right for them to grow. Henbit, Chickweed, Oxalis, and Dollar weed are all broadleaf weeds you can find in just about any lawn this time of year. When our lawns go dormant these weeds start the process of filling in the weak areas of turf you have in your lawn. Another problem this time of year is that commercial lawn care companies tend to cut the lawns much closer to the base of the plant during the cool season providing additional openings for weeds. The more light reaching the soil surface the more weeds you will have. Some homeowners try to cover the open areas or thin areas of their lawns with a winter groundcover like Rye grass.
Winter Rye grass seed can be used very effectively to fill in bare, thin, or shady areas of the lawn which will help crowd out the broadleaf weeds that want to grow. Whether you have a Bahia or St. Augustine grass lawn, you can purchase rye grass seed and broadcast the seed in those areas of your lawn where weeds have grown in the past. The northern exposures of your home and areas that get only morning sun are very susceptible to heavy weed pressure during the winter months. You can apply winter rye grass seed to these areas in November through February. I like to purchase my winter rye grass seed from a local Feed store or garden center. When you apply the seed to your lawn you will need approximately seven to ten pounds of rye grass seed for every one thousand square feet of area you want to cover.
I like to use a rotary hand held spreader when applying my seed. Rotary spreaders are easy to use and give a consistent pattern. You can also direct the seed to smaller areas that are not usually accessible to large rotary spreaders. Please do not worry about covering your entire lawn with this seed as you only need to cover those areas that are thin as noted above. Even though some people do go over their entire lawn to give the appearance of uniformity, remember this type of grass is only temporary and will slowly die out when the temperature rise into the mid-eighties around April. Rye grass seed germinates very quickly, usually in about two weeks. Make sure that you have not applied any type of weed killer to your grass prior to spreading out your grass seed as the seed may not germinate if a weed killer has been applied to your lawn.
Weeds are essentially defined as a plant out of place. Reducing the number of weeds and weed seed pressure should be a goal of every homeowner. If you let a weed grow to the flowering stage then the seed produced from that weed will add to the seed bank your lawn already has. By monitoring your lawn regularly and applying herbicides as needed before the weeds reach maturity, you can reduce the overall seed bank pressure in your lawn. Walking your lawn regularly to identify weeds as they are just starting to grow and then controlling them at the early stage will greatly reduce the number of weeds you will have to fight in the future. In order to control your existing weeds you will first have to determine which type of grass you have and then select the proper herbicide to control the weeds for your specific grass type.
If you do not know what type of grass you have you can take a sample of the grass growing in your yard to the local extension office in your county for proper identification. I can not stress how important this is to know what type of turf grass you have as the herbicides you will need to apply to your lawn can kill your turf grass along with your weeds. If you apply a St. Augustine weed killer on a Bahia or Zoysia grass lawn then you could possibly kill your good grass along with the weeds. The same holds true that if you apply a Bahia weed killer on a St. Augustine lawn, then you could kill the St. Augustine lawn as well.
When picking out a product to kill the weeds, look towards the liquid weed killers. Liquid weed killers can be applied with a pump up sprayer and directed to where the weeds are the heaviest. The weed killer active ingredient for St. Augustine Grass is called Atrazine. The Active ingredient for Bahia and Zoysia grass is called 2-4-D or Dicamba. Always read the entire label for special instructions. Look for these ingredients to be listed on the front of the label of the product you purchase. Also, when mixing these products with water, always wear gloves and safety glasses. Just before you apply these products, add a little dishwater detergent to your pump up sprayer such as Joy, or Dove. Use about a teaspoonful per gallon of water. After you add the dish soap make sure you shake the spray container well. The addition of this detergent will help to spread the product evenly over the leaves of the weed and give you better control. Remember, killing weeds on Bahia grass will only take about a week. St. Augustine weed control usually takes 4-6 weeks. Don’t be impatient!
Remember, the herbicides I listed above are for the control of broadleaf weeds or weeds that look like weeds. Weeds that look like grasses such as carpet grass, Alexander grass, Torpedo grass, and sedges will not be controlled with these products. These grassy weeds require specific herbicides and timing to control and I will have to cover them in another article. Because these types of weeds are the hardest to control, they are best left up to a professional pest control company to control.
Winter is a great time of year as you have more time to inspect your lawn for weeds between mowing. Add winter rye grass to bare areas of the lawn to reduce weed pressure. If you are going to treat your weeds yourself then make sure you read the label closely. Leave weed grasses and sedges up to the professionals to control for you. Good luck in monitoring and controlling your lawn weeds and remember, without plants we would not be here! Thanks again!

3 thoughts on “Weed Control

  1. Byron Newcomb says:

    Great article, but what can I use as a weed killer to kill sedge that is growing in my Empire Zoysa grass

    1. mgovan says:

      To control sedges in your Zoysia grass you should try a product called
      Sedgehammer. This is very effective! Good Luck!

    2. Mark Govan says:

      You need to try Sedgehammer. This product is available at most garden centers!

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