Neil Sperry column: Live oak’s recovery from radial shake takes time (2024)

Dear Neil: I have two live oak trees in my front yard. Both were damaged by the February 2021 cold. One of them looks really bad in its lower trunk. Is it “doomed?” It is as green as normal at the top. It’s about 50 years old. What should I do?

A: I can see why you’re concerned. That is substantial bark loss. However, the canopy of foliage is better than many live oaks that were hurt by the cold. I’d get a certified arborist on site to examine the trunk closely. It’s possible that there is a good bit of healing from this “radial shake.” (That’s the name given to this bark loss that resulted from the prolonged and extreme cold.) As long as the canopy stays relatively full the tree is making progress. It’s when it begins to thin month by month that you need to worry. Other than routine care of watering and modest feeding, there is nothing you can do to help it along. The arborist would know if it presents any risk of falling.

Dear Neil: I think you addressed this a year or two ago here, but I didn’t save the column. I have Texas mountain laurel seeds I would like to grow. Do I soak them or scar them?

A: You need to “scarify” them. That’s a name given to mechanically breaking through their outer, rock-hard seed coats. I use a pair of pliers and carefully place one seed in them at a time. Then with my other hand I use a three-cornered file to cut through the seed coat. As soon as I see the creamy yellow embryonic tissue, I stop. When I’ve done all the seeds, I soak them overnight and plant them into 4-inch pots the next morning. I use a lightweight potting soil to get them started, and each pot gets one seed inserted about 1 inch deep. Water the potting soil and put the flat filled with pots out in the sun. Almost all of them will germinate, and they’ll do so quickly.

Dear Neil: We replaced a portion of our Asian jasmine that winter had killed, but now we have a very fine grass growing in it. Is there any kind of weedkiller that will kill the grass without killing the jasmine?

A: Yes, there is. But the last time I checked, what I’m about to mention was not listed on the product’s label, so I cannot legally recommend it to you. I will merely tell you that I have seen hundreds of landscape contractors over dozens of years use this way of getting bermudagrass out of Asian jasmine beds when they thought they were going to have to start over completely. Please understand that this is merely an observation and not a recommendation. You assume all the risk. It is to use a glyphosate-only herbicide to spot-treat the weed grass. Glyphosates are grass killers. They do not seem to harm mature Asian jasmine once its leaves have turned dark green and leathery. Your plants may still be too immature. You would have to be careful to avoid products that contain glyphosate in combination with other herbicides, because those other weedkillers most definitely would kill the jasmine. That’s why I pointed out that the contractors use specifically “glyphosate-only products” and at the recommended rates for killing bermuda. I have used this on several occasions with excellent results and without any damage to my jasmine. But again, you assume the risk. You might try a small area first to be sure you like the results. (Note: verify that the weed is a grass and not a sedge. A Texas Certified Nursery Professional can assist in that identification.)

Dear Neil: I just read your article about wrapping the trunk of my new Autumn Blaze maple. You answered my question! But now I wonder if I need to change it every so often. Does it stretch with growth?

A: I use the specialty product, a paper tree wrap, that does stretch with the thickening of the trunk. Plastic wraps that clasp around trunks also expand as the trunk grows, so they would be fine as well. The reality is that you won’t have the wrap in place more than a couple of years, so it won’t be a long-term issue.

Dear Neil: I have three 4-year-old crape myrtles in my backyard. Last year they were full of blooms, but this year only one has flowers. They are in a part of the yard that remained really wet this spring. They also have a powdery substance on their leaves. What should I be doing?

A: I’m part of an organization that has planted more than 30,000 crape myrtles in one Texas city, and I can tell you from that experience that their bloom dates vary by several weeks, both variety by variety, also from year to year. If these are all the same variety, then it probably would be something environmental, and poorly draining soils would be as good a guess as any. This year’s rainy spring and early summer has delayed their bloom by several weeks. Also, if you topped them in any way (never a good plan), that will also delay flowering by as much as six or seven weeks. I would be more concerned about how much new growth they are putting out. If they’re growing vigorously, you’ll be just fine. As for the powder, that’s powdery mildew. It is disfiguring, but it rarely does major damage to the plants. It’s “original factory equipment” with older types of crape myrtles. It will soon abate.