We have many large post oaks that are slowly dying--selected leaves turn yellow and then the whole tree dies. It seems to be spreading from tree to tree, so maybe it is a fungus through the root system. I know that Post Oaks are not real susceptible to Oak Wilt, but that is what it seems to be. Any suggestions?
Help!!! My big Post Oaks are Dying!
hi Janbassi,
I have always heard that post oaks planted in an irrigated lawn can succumb to the moisture. Apparently they are better suited to dry sandy or rocky soil. I'm including a link to the aggie horticulture article that speaks to how unhappy they are with root disturbance and lack of oxygen to the root zone.
Pam
http://aggiehorticulture.tamu.edu/ornamentals/natives/quercusstellata.htm
Janbassi, I've noticed that some Post Oaks in the nearby Lost Pines area are also dying. Contact the Texas Forest Service near you. If you click on either Insects and Diseases or Urban Forestry in this link, you'll get contact information for your country.
http://txforestservice.tamu.edu/main/article.aspx?ctrl=14
They will come out to your property to look at your trees and the problem.
Well, I live between Bastrop and Elgin, and most of our big trees are post oaks. Right after buying our land, we started seeing some of the big oaks die off. The foilage would brown out very fast, and all the bark would start falling off, right in a big pile at the base of the tree. I contacted the local extension agent, and he said without a doubt it was Hypoxylon canker. I checked it out, and I agree. Chances are all of your trees already have it, but it only effects trees that have been stressed. From what we have seen in our area, the two biggest stresses are drought, and human activity. If you do any tractor or gardening work around your post oak, it increases the chances it will die. We can see this easily where we cleared driveways and ranch roads. Anywhere the dozer went, 1/3 of the trees died. My advice, stay away from the trees (no mowing, gardening, etc), and start replanting trees other than post oak. We have a few books about TX gardening, and they say do not plant post oak as a landscape tree. I agree. Go with burr, red or live oak.
Here is a link:
http://txforestservice.tamu.edu/main/article.aspx?id=1262
When I was looking for Post Oak diseases yesterday, I ran across a website post by an arborist. It listed the oak affected, the disease and the symptoms. The symptoms listed for Hypoxylon canker matched what you described and as eltex said stressed trees are the ones that fall prey to the canker. Diversity in planting is the answer. We have mostly large live oaks that are irreplaceable should Oak Wilt get them. The few Post Oaks we have are scattered throughout the wooded area of our ranch. Fortunately, the woods are very diverse with lots of other native trees. We are trying to be very careful as we remove the mesquite that has moved into the open areas and the woods. It's going to be time consuming because many are located just in from the drip area of the large live and post oaks. Those will have to be cut and the cut surfaced painted with an herbicide, probably many times as the things resprout. We lost most of our Water Oaks in 2002 - 3 to stress (brought on by drought) related diseases.
I must admit to planting more oaks, although most are burr or southern red oaks (I've found these are harder to establish in our cyclic drought prone area.) Ideally, we need to plant trees other than oak.