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Aug 31, 2023

Sperry: Oak still affected by past freeze damage

Dear Neil: I bought this oak tree 10 years ago. I’m not sure what is going wrong with it recently. It’s not right by the house but it’s close to the driveway. Can it be saved? Answer: There appears to

Dear Neil: I bought this oak tree 10 years ago. I’m not sure what is going wrong with it recently. It’s not right by the house but it’s close to the driveway. Can it be saved?

Answer: There appears to be a lot of “radial shake” still showing up in the bark. That’s the term referring to damage done by the extreme cold of February 2021. Bark is still coming off oaks all across Texas in large sheets. The bark separates exposing interior wood and severing the phloem tissues that are critical for transporting sugars down to the roots. From your photos I’m also seeing narrow branch angles that could soon become weak points in the branching structure of the tree, as well as spots that look like active decay. I would strongly suggest that you get a certified arborist on site as soon as possible to determine the nature and extent of the problems over the entire tree. It’s impossible to tell from just the narrow visions in your photos.

Dear Neil: I knew we were pushing the window by planting two new shade trees in April but I’m usually good at keeping plants alive. The bur oak in the backyard is doing well. It has some shade from large pecans next door. However, the poor red oak in the front yard gets no shade from the western sun and it is struggling. The twigs are still flexible but the leaves appear bleached. Is this sunburn? What should I do?

Answer: This is not sunscald. This looks like a tree that simply got too dry one or more times and turned brown because its leaves were lost in the process. Sadly, we saw a lot of this with new trees and shrubs last year and this year. People may have forgotten to water them by hand so that they could soak the original soil balls deeply. The original root systems are still pretty much together, so it’s imperative that we keep them thoroughly soaked with a garden hose and a water breaker or water bubbler. If the tree came out of a 30-gallon pot, it should be getting 30 gallons of water every other day spring through fall.

By comparison, “sunscald” shows up in the second and especially the third year when a red oak (or red maple, Chinese pistachio or other thin- barked tree) is planted without having its trunk protected with paper tree wrap. I use the term “non-negotiable” to emphasize that without such protection the bark on the west and southwest sides of the trunk will gradually dry and split like old, weathered leather. Internal tissues will be exposed, and borers and decay will move in. This happens because new trees that have had their trunks shaded by one another in the nursery are suddenly forced into the sun when planted out into our landscapes. You can try wrapping your tree now, but it may be too late.

Dear Neil: I wrote to you earlier this spring about growing Texas mountain laurels from seed. I followed your advice, and now I have three little 6-inch mountain laurels. No questions. Just wanted to tell you I was grateful for the help.

Answer: I’m glad it worked. I’ve done the same things I shared with you (filing just through the seed coats, soaking the seeds overnight, and planting in pots). They’ll grow slowly and you’ll need to protect them from cold winter weather but you’re on your way.

Dear Neil: Our redbud is about 10 years old and it appears to be in distress. It has been losing leaves but now the pace has really picked up. It has so many yellowed leaves and many are falling. Can you see what the problem might be?

Answer: Redbuds have relatively short life expectancies compared to other shade and flowering trees. It appears that this tree has already died back to the ground at some point years ago owing to the number of trunks coming up from what was its original base. I’ve seen this happen hundreds of times, and then the second-generation trunks develop for 10 to 20 years, but gradually fade as they become congested. I couldn’t tell from the photo if there is any decay in the cluster of trunks but it looks like there could be. My suggestion would be to keep the tree properly watered the balance of this season and winter. See how it comes out next spring, then decide if it’s time to replace it. (For the record, the spotting that is showing up on the foliage is very minor. You’ll see it on every redbud in Texas by the time fall arrives. It is fungal but I’m not even sure which fungus. You would have to have it cultured through a pathology lab but I don’t think it’s worth spending money on at this point.

Dear Neil: My ponytail palm has been healthy and vigorous for years. How can I restore it to its old self?

Answer: When I first saw your photo of it in its pot, I thought it was submerged in water! I was going to tell you to rush to get it out. I may still offer a variant of that advice by suggesting repotting it into a heavy terra cotta pot that can serve as its base and support. You might even have to devise some hidden means of anchoring the swollen base to keep the plant from toppling over, but it needs to “ride” the top of the soil. Use a lightweight, very porous potting soil. You could even combine 10 or 15 percent expanded shale with your potting soil mix to give it yet additional ballast. Put the plant in a bright spot out of direct sunlight and feed it with a high-nitrogen, liquid fertilizer diluted to their instructions.

Be certain, however, that your new pot has a drain hole so that you can water heavily to leach excess mineral salts (from fertilizers, tap water, etc.) out of the soil. Do that at least monthly. Use small, very sharp scissors to trim the unsightly congested top foliage. As new growth emerges, carefully remove all disfigured leaves.

— Have a question you’d like Neil to consider? Mail it to him in care of this newspaper or e-mail him at [email protected]. Neil regrets that he cannot reply to questions individually.

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