Texas Root Rot is a fungal pathogen that is indigeneous to soils in the Southwest. The fungus does not move in the soil. Instead it must 'hitch' a ride on a root that grows into its location. Then it slowly invades the tissues of the root where it causes failure of the vascular system of the plant. If one plant's roots touch anothers, it is possible for TRR to move from one plant to another via the roots.

TRR is not causing the problems you are experiencing with your trees. It usually takes at least a year for a tree planted in an area with TRR for symptoms to appear. This is because the roots have to grow into the area with the fungus as mentioned above.

Your problems are probably water-related. If the root ball dries out, or if the root ball was damaged during planting it would cause the symptoms you describe. When you apply water you must moisten the entire root ball and then let it dry just a bit before the next application. You don't mention how you are delivering water. Do you use a drip system or a hose? If a drip system you will want to water for at least two hours each time with the intent to push the water to a depth of three feet. If using a hose, just let the water trickle for several hours - at night works well because the water in the hose stays cool. This will depend on the size of the original containers. If you planted 24 inch box trees, you will need to water for a longer period of time.

The only way to test for TRR is to dig (not pull) pencil-sized roots, with soil attached, and take them to a laboratory. Do not add water, but keep roots cool in a plastic bag. The lab will look for the fungal strands attached to the exterior of the roots.

Good luck.

Certified Arborist

Here is a link that might be useful: Cotton (Texas) Root Rot