Ask Mr. Smarty Plants

Ilex vomitoria (Yaupon) is ordinarily a very low care plant. This USDA Plant Profile shows it growing no farther west than Travis County. We have grown it very successfully in both Tarrant County and Washington County, but neither of those is east of Travis County, either. So, it could be that your soils in Tom Green County do not entirely agree with it. If you follow the plant link above you will learn that its preferred soil description is moist, well drained, sandy, loamy, clay, limestone, or gravelly soils. "Well-drained" is probably the operative word there. If you dug a hole for the plant and added no compost or other organic material and the soil is clay, it is probably not draining well enough to suit the roots of this low-water consuming shrub. The roots may be drowning, especially if it is receiving the same watering that the lawn is.

However, it is the wood chips that you have repeatedly put on the plant's base that draws our attention. If you are using chunks of wood, instead of good-quality shredded bark mulch, we suggest you read our How-To Article Under Cover with Mulch. Note especially that it is recommended that any mulch be pulled away a few inches from the trunk of a woody plant, such as yaupon. Also, be aware that one of the advantages of such a mulch is that it will decompose slowly and go into the soil to improve the texture, access to nutrients and drainage for the plant. A chunky mulch that is not organic, that is, has not been composted before being used, will still decompose but much more slowly and can pull nitrogen out of the soil in the process.

Although many things, including age, can cause yellow leaves, frequently it is the result of chlorosis. Please read this article from the University of Illinois on Chlorosis, which often is the result of nitrogen deficiency in the plant. We would suggest you pull off the mulch presently there and replace it with fresh composted shredded bark mulch.

In the process, clean out under the shrub. Mulch can shelter insects and weeds. Frankly, we have no idea what the plant is that you have pulled out from under it, but it is not contributing to the yaupon's welfare, no matter what it is. Pull it out, or cut it off as close to the ground if you can, and continue to do so. Whatever it is, it will continue to try to survive.