News Article for June 15, 2009 from LSU AgCenter County Agent Kenny Sharpe::
I have had a number of calls from around the parish from people who are losing mature trees for no apparent reason.
You will remember that last year we had a visitor named Gustav. I am not certain all the calls I have received are hurricane related, but I will tell you that the year after Hurricane Andrew we lost a tremendous amount of mature oaks, other hardwoods and pines.
One of the conditions that occurs during a hurricane is root tearing. In the most severe cases the trees topple over and pull the roots out of the ground. There certainly were lots of uprooted trees after the storm. You might assume the trees that did not topple were all right. That assumption would probably not be correct. In the strong winds of a hurricane you get a lot of roots that do tear as the wind puts constant pressure on the trees, usually from one side.
The following year you have limited roots to support the full canopy of leaves. Add to that the heat of summer and then dry weather. It is then that the trees get the full brunt of the stress. Many buckle under the strain.
Usually you will see the terminal ends of branches start to die back. I have, however, seen healthy-looking, mature trees go from full green to totally brown in a matter of a few days.
My suggestion would be to water in the absence of rain to ensure your trees get adequate water. Just include the trees in your watering pattern for your lawn. It is always better to water thoroughly once per week than to water lightly several times. This will allow for deep irrigation that will prompt the roots to stay deep and seek out water reserves held in the soil.
If you get 1 to 2 inches of rain in a week you can skip watering. When your trees are sucking up so much water that the grass under them is starting to roll up then you definitely need to be watering.
Another potential problem of stressed trees and dry weather is ips beetles on pines. These beetles are specific to pines and will appear when trees are stressed and especially in dry weather. You will notice them first after they bore into the side of the trunk and create a small pitch tube which will form a small mound of pine sap that looks like a piece of popped corn. The next sign will be saw dust at the base of the tree, and then the final sign is the needles turning brown.
You may be able to stop the initial infestation with a broad spectrum tree insecticide applied to the bark if the beetles enter the tree below 10 feet. Once the needles turn it is too late.
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One other dry weather concern is chinch bugs in you lawn grasses. They will feed on the plants in dry weather and will cause large brown areas. Usually chinch bug damage will not be circular, like brown patch, but more jagged and irregular. Look down in the grass at the roots for chinch bugs. They are about 1/16” long black with white forewings. Treat with Sevin or Talstar.
For more information on these or related topics, contact Kenny at 225-686-3020.