Gardeners' Dirt: Weather wreaks havoc on lawns
By Charlie Neumeyer - Victoria County Master GardenerEdited by Charla Borchers Leon
April 7, 2010 at midnight
Updated April 6, 2010 at 11:07 p.m.
Editor's note: In the past couple of weeks, the Victoria AgriLife Extension office has received many calls from residents with concerns about their lawns. The weather itself is a factor, but temperatures and moisture also exert a strong influence on other factors that can negatively impact turf grass. This is the first of a two-part series on turf-related issues.
This past year has really been an unusual one in respect to the weather. We went from extremely dry conditions with very high temperatures, to extremely wet conditions with very low temperatures.
Weather extremes such as these are hard on all the plants in our yards and gardens and the lawn is no exception. Hot, dry conditions favor a bumper crop of chinch bugs, while wet, cooler conditions promote the growth of brown patch and take-all patch.
To say the least, your yard has been stressed to the max over the last year.
Due to the extremes of weather that we experienced the last growing season, our turf grass did not go into the winter in excellent condition. We went from dry dusty conditions to extremely wet conditions.
When the rains began, low areas in your lawn may have been inundated and stayed submerged for extended periods of time. All of this took a toll on your lawn.
Unless we have an unseasonably warm winter, there is always some die-off in turf because of cold temperatures. Since the turfs common to this area, St. Augustinegrass, Bermudagrass and Zoysiagrass, are warm season turfgrasses, they will go dormant when winter sets in, so even though the lawn may look dead, it is in reality just "sleeping." This is a natural mechanism on the part of the plant to cope with cold weather, especially for Bermudagrass.
Locally, cold temperatures are generally not a factor when it comes to our lawns. However, according to Texas AgriLife Extension Service, some varieties of St. Augustinegrass tend to be more sensitive to extreme cold (below 20 degrees) than Bermudagrass and Zoysiagrass.
The cold winter that we experienced may have had a greater impact on sod that was weakened by drought, chinch bugs, fungus or a combination of all three.
If you look at weather data over the past few weeks, you can see that our temperatures have remained very cool.
Area lawn turfs are called warm season for a reason. They prefer night time temperatures above 65 degrees and daytime temperatures in the 80-degree plus range.
Our mornings are still in the 40 to 50 degree range, and we've had only one morning in the mid-60s. Daytime temperatures have also remained cool.
So, while it appears that some lawns are dead, in reality, they just haven't completely come out of dormancy yet. It may not be panic time yet.
Is It Still Alive or Dormant?
If you did not water your lawn through the drought last year, there is a very good chance that your lawn, or at least some areas of your lawn, will not green up this spring. If you have St. Augustinegrass or a Zoysiagrass, the easiest way to determine whether the grass is alive is to look at the stolons.
Using a leaf rake, vigorously rake through several areas of your lawn to remove all of the dead blades of grass. Examine the stolons for signs of life. If the runners are green, or have some green in them, then the grass should make a comeback.
If you do not see any green in the stolons, dig up a small section and examine the roots. The roots on viable stolons will be white or off-white, pliable, and have numerous small feeder roots coming off the main root.
Dead roots will be brown, dried up and sort of stiff.
If you have green stolons and the roots are alive, your grass is still dormant. If your roots look like the latter description, you will be replacing your lawn.
While Bermudagrass does have some above ground stolons, they are not really an indicator of whether the grass is dead or alive. Instead, you have to look at what is below ground; their roots including rhizomes (underground runners). Using a shovel, dig a clump of your lawn and check the underground runners. If they are white and pliable, the Bermudagrass lawn will come back. Bermudagrass stolons will typically freeze each year with the rhizomes resulting in the spring comeback.
Chinch Bug Damage
Chinch bugs will be long gone now, but their damage will remain. Look at your lawn, particularly near the driveway and walks. If there seems to be more dead grass in these areas, there is a good chance that you were hosting chinch bugs during the hot, dry part of the year. Once again, the stolons will reveal the extent of the damage. If they are brown, the grass is probably a lost cause. If there is still some green, the grass will come back.
Brown Patch Damage
Once the rains began last fall, the brown patch fungus began to thrive. The cool, wet fall that provided an ideal growing situation for brown patch and take-all patch. If you have circular areas in your lawn that appear to be "more dead" than the rest of your lawn, this is probably the result of brown patch.
Using your rake or your fingers, pull away the dead grass and look at your runners. If they are green, the area was probably infected with brown patch. The lawn will recover, but more slowly than the rest of the lawn.
If you have large irregular splotches and the runners in this area are brown and dead, the most likely culprit is take-all patch.
Next week's column will discuss treatment for this type of damage.
Regardless of the type of lawn you have, by now you should have mowed at least once. Mowing, along with warmer, longer days and nights, will stimulate your lawn and you should see significant green growth shortly.
Until next week, dig your fingers through your grass and soil to evaluate your situation and we'll discuss more related topics next week.
The Gardeners' Dirt is written by members of the Victoria County Master Gardener Association, an educational outreach of Texas AgriLife Extension - Victoria County. Mail your questions in care of the Advocate, P.O. Box 1518, Victoria, TX 77901; or firstname.lastname@example.org, or comment on this column at www.VictoriaAdvocate.com.