Ask Mr. Smarty Plants

Ungnadia speciosa (Mexican buckeye), Quercus muehlenbergii (chinkapin oak), and Ehretia anacua (knockaway) are all native in or near Travis County, so you don't have your trees in the wrong area. Since we are not plant pathologists and can't actually see the tree, this is going to take some detective work, and you will have to be the detective.

First, when you say you transplanted these trees recently from a sheltered environment, how recently? Was it last week, a month or so ago in the midst of our cold snaps or last summer when we were having record heat? Since all three are showing signs of stress, the problem may be the same for all three. Coming from being grown indoors to the much less forgiving environment of outside, they could very likely  be suffering from transplant shock. Transplant shock is a pretty broad category and could be caused, at least partly, by sudden temperature changes, by putting fertilizer in the hole where it would shock the little roots, or by planting them in a poorly-draining clay soil.  When you asked if there had been not enough watering, with the recent rains we have been having, that seems unlikely, but if the soil is not draining, the roots could be drowning. 

As for insects, have you seen evidence of any insect activity? Holes, swelling on the leaves, tiny spots on the underside of the leaves? We will give you websites that have pictures and can tell you a little about some of the most frequent bug villains to threaten new young growth. Don't, please, go to the nursery and ask for a spray. That could hurt the young trees far more than any possible insect. Many insects can be controlled with a spray of water on the leaves. This early in the season, we think you can discount insect damage, but it doesn't hurt to check.

Possible Insect Pests: 

University of California Integrated Pest Management - thrips

University of Minnesota Extension - scale insects

University of Missouri Extension - whiteflies

University of California Integrated Pest Management - aphids

Colorado State University Extension - spider mites

Finally, on the watering: stick your finger down in the soil around the tree roots and see if it feels very dry, nice and moist or very wet. If it feels nice and moist, and not compacted, leave it alone, it's fine. If it feels very wet, the drainage is probably bad, don't water it. You might try putting some good quality shredded hardwood mulch on the soil. That will protect the roots from heat, and as it decomposes, add some more organic material to the soil to assist with the drainage. If the soil feels loose but is dry, stick a hose way down in the hole, and let it run at a slow dribble for an hour or so or until water appears on the surface. If the water stands on the surface for more than thirty minutes, we're back to the drainage problem. 

So, what to do? Unless you discover an obvious insect or water problem, it still looks like transplant shock. You didn't say how tall the trees were or if there were any healthy leaves, but try trimming off about 1/3 of the upper portion of the tree, leaving some leaves for providing nourishment to the tree. Remember, no fertilizer until the trees seem well-recovered. Fertilizer would force the tree to try to put on new growth, which would be even more stress on an already-stressed tree. Trimming some of the upper growth will, again, take away some of the stress on the roots. Beyond that, since these are all trees native to this area, there is hope that they will adapt and grow up to be big native trees.

From our Native Plant Image Gallery:

Ungnadia speciosa

Quercus muehlenbergii

Ehretia anacua