How to kill horseherb in zoysia and move Texas mountain laurel

Q: I have a 3.5-acre piece of property, and this ground cover grows wild over a good portion of it. I have two areas, however, where I planted and maintain Palisades Zoysia around my front walk and pool. This plant is starting to invade the grass around the pool. Is there a way to get rid of it in that space without harming the grass?

MORE SPERRY: Cracking the shell on pecan tree decay

A: Absolutely. You have a native Texas plant called horseherb (Calyptocarpus vialis). It's been touted as a good natural ground cover, which sounds like your experience exactly. Many people use it as an alternative to turfgrass in very low-maintenance areas. My own personal experience with it in my rural landscape is that it is very invasive. I planted 30 to 40 plants in one area one spring, and within two years they were showing up in purple wintercreeper euonymus groundcover beds 500 feet away (and uphill). Plus, it's deciduous, meaning that half of the year the bed is bare down to the soil. Nonetheless, it's pretty when it's in the right place.

As for eliminating it when it gets into turf, apply a broadleafed weedkiller containing 2,4-D. Most such products contain two other herbicides intended to kill nongrassy weeds. Any of those products should make short order of the horseherb. Read and follow label directions to avoid damage to desirable trees and shrubs nearby.

Q: Can I move one of my mother's Texas mountain laurel shrubs now? She is moving and wants to take it with her.

A: It probably would not survive the move. At this point in late spring, trees and shrubs have expended all their energy putting out new spring growth. Hot summer weather is soon to follow, and if you were to dig and cut a major portion of the plant's root system, it would just be too much trauma. See if you can arrange to go back in the winter and move it for her. That would allow you to "root-prune" it by severing lateral roots all summer and fall, encouraging new roots to form inside the soil ball.

Q: Attached are two photos of our wilting redbud tree. It has plenty of water. Thank you.

A: Oh, my. That's not many facts to get me started. Let me do the best I can with what I have. First, it should be noted that whatever the problem is, it's in the roots or the trunk since the entire tree is impacted.

If I were coming to your landscape, I would first look at the other plants nearby to see if any of them seemed to be suffering similarly. From your more distant photo, it does not appear that that is the case. Therefore, I'll assume the soil moisture is indeed satisfactory.

I would look closely at the trunk of the redbud to see if there might be visible damage to its bark. Is there any sign of decay? More likely, are there any pencil-lead-sized holes in the bark? Those would suggest presence of red-headed wood borers. They are common visitors to redbuds and silver maples. It's been my observation that they seem to have an early sense of any impending crisis in these trees' vigor. By the time the borers are present, the trees cannot be saved.

I would check the root flare of the trunk to be sure it's not planted too deeply. You should be able to observe where the trunk begins to spread wider (flare outward) as it enters the soil. Exposing the roots closest to the surface sometimes helps, but usually by the time the tree is wilting this badly it's too late to make a difference.

Finally, I would be concerned about any herbicide or pool chemical that could have been spilled around the root system of this tree. Again, however, the surrounding plants would have been affected.

If you can't find something obvious, it's probably time to call for an on-site visit from a certified arborist. Unfortunately, without a great deal more information, that's the best I can do to help you.

Q: I have access to a lot of shredded paper. We normally send it to recycling, but I've wondered if I could use it in the compost?

A: I send ours to recycling. It is organic matter, so, yes, it could be put into the compost. However, normal life byproducts like shredded tree leaves, grass clippings, animal manure, finely chipped wood, and others are better things to put into the compost. Paper breaks down very quickly, but you'll need to wait on the other types of organic matter to decay before you can use the compost.

Q: Can I root cuttings of my boxwood plants in water?

A: Yes, probably so, but that's not the best way. Roots that develop in water are accustomed to having limited oxygen, and when they're transplanted into potting soil, they often wither away.

It's better to use a mix of equal amounts of sphagnum peat moss and horticultural perlite. Water it thoroughly before you start sticking the fresh cuttings. The cuttings should be 3 to 4 inches long. Strip off the bottom leaves and dust the stems in rooting hormone powder. Use a small stick to make each insertion hole so you don't wipe off the powder.

Spray/soak thoroughly, then cover lightly with a sheet of dry cleaner's plastic (not air-tight). Put in a bright spot, but out of direct late morning and afternoon sun. For what it's worth, if there is a lot of brand new, succulent growth on the tips of the twigs, pinch it off. It will draw water out of the cuttings before they have time to form roots.

When your cuttings have formed roots, dig them and pot them into quart pots, two or three cuttings per pot. Grow them in those containers the rest of the summer and early fall before repotting them into 1-gallon pots.

Email questions for Neil Sperry to [email protected].

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