Common Lawn Insects and Weeds

Now that we know how to establish a healthy lawn, let’s talk about some potential insect and weed issues that we have had problems with in recent years. For insects we need to watch for signs of chinch bugs, armyworms, and tropical sod webworms. Chinch bugs have been commonly seen in St. Augustine grass and bermudagrass lawns. They typically show up during hot, dry weather and form yellowish-brown areas in your lawn.

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Chinch bug on blade of grass.

To determine if you have chinch bugs, saturate the infected areas with a gallon of water mixed with a few squirts of lemon dishwashing soap. The soapy solution brings them to the surface where you can identify if they are causing the damage to your lawn. If you do have chinch bug infestations the LSU AgCenter recommends treating the infected areas with insecticides containing Pyrethroids, such as Advanced Lawn, Bug-B-Gone, Deltaguard, Talstar, etc. Additional insects that show up during the summer months include army worms and tropical sod webworms. In recent years we have had severe infestations of tropical sod webworms in Pointe Coupee. The LSU AgCenter recommends treating sod webworms with insecticides containing the active ingredient, Carbaryl. Remember to always follow the manufacturer’s label.

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Virginia buttonweed mat in your lawn.


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Virginia buttonweed from fruit (seed pod) to matted growth.

One common weed that has been showing up in late spring and early summer is Virginia buttonweed. This weed is well adapted to our area and soil types. It is spread primarily by seed but can also spread vegetatively, which means that it cannot be mowed out of your lawn. Its seed can persist in the soil for many years and typically loves soils that hold moisture. The LSU AgCenter recommends hand pulling this weed and discarding immediately when it is first seen in the lawn if only in a few locations. To reduce it from being spread across the lawn, first make sure you are following all recommended cultural practices and remove excess moisture from your lawn. This will reduce its infestation in future years. An herbicide program approach works best to control Virginia buttonweed. To manage the weed you must start in early spring. The beginning of April is a good time to begin to spot spray with applications of mecoprop; and carfentrazone. Herbicide applications during the spring will kill germinating seedling plants and injure perennial plants. Once temperatures exceed 85 degrees Fahrenheit, we should no longer apply herbicides containing 2,4-D, as it will cause too much injury to St. Augustine grass and centipede grass. During the summer, metsulfuron or products such as Celsius, should be applied. Always repeat metsulfuron or Celsius applications four to six weeks after initial application. Single herbicide applications, especially late in the season, have not been effective on mature Virginia buttonweed. Again, when using any herbicide or chemical, always follow the manufacturer’s labeled directions.

For further assistance on this topic, please contact Mark Carriere, Associate County Agent, by calling (225) 638-5533 or via email at mcarriere@agcenter.lsu.edu. You can also find more information by visiting www.lsuagcenter.com.

5/15/2020 7:38:12 PM
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