GARDENER'S MAILBAG: What is eating my lacey oak?
Dear Neil: What could be causing these spirals of holes in the trunk of my Lacey oak? The tree seems to be healthy. It had small acorns that dropped early, but that might be due to last winter’s cold.
You’ll be relieved to know that this is nothing more than the work of one or two woodpeckers. They work their way around the trunks of trees, and oaks and pecans are two of their favorites. I have a Lacey oak along our drive, and I could just as easily have taken this photo of my own tree. They do no particular harm, nor do they suggest any type of problem. They come back later and feed on the sap that flows from these wounds. There is no call to action unless the problem gets a lot worse. In that case you could apply black pruning sealant.
Dear Neil: This vine is taking over a big part of our landscape. We were gone for a while this summer, and when we came back, it had twined over many of our shrubs. I’ve tried spot-treating it where I could, but there is so much of it. What is it, and how can I control it?
It’s called “creeping cucumber” (Melothria pendula) and it’s common across big parts of Texas. It’s a perennial vine, so you’re not only going to have to contend with its seedlings, but also with spreading roots. I have it in my landscape from time to time. I cut the plants off at the ground, reaching in beneath my shrubs with a sharpened hoe to scrape it off. Then I cover the beds with roll-type mulch that I cut and fit to overlap at the seams. To make it look better, I finish it off with either pine bark mulch or with shredded tree leaves. That has worked on this vine, also on wild morning glories and snailseed vines.
Dear Neil: We have had a planting of dianthus in our flowerbed for probably 15 years. They have done really well until this year, but now they are turning yellow and dying out for some unknown reason. We have not made any changes. What might be causing this?
My guess would be one of the water mold funguses that attacks at the soil line. Chief among them are Pythium, Rhizoctonia and Phytophthora. You can often see where the disease has attacked the plants’ stems at the ground line, often making them look like they’ve been pinched with hot tweezers. However, you would need a lab test to confirm these. There is also the possibility that the soil has become compacted and challenging for good root growth. When you have perennials that don’t require digging and dividing regularly, that can become the result. Obviously, I don’t have a firm answer for you, but hopefully those will give you a start.
Dear Neil: I planted a maple last fall. It had pretty red foliage when I planted it, and I thought I watered it enough. It put out new leaves this spring, but by July they were fading. If a tree is starved for water early on, can it ever recover?
Unfortunately, your photo files were listed as “empty,” so I don’t know how the tree looks. If it has lost all of its leaves from this year, you can hope that it will send out new shoots from its base. If it does, select the strongest straight shoot and train it to be the new trunk. If you don’t have any new growth by spring, it’s time for another tree.
Dear Neil: How much cold will bougainvilleas tolerate over the winter? Can I keep two large ones in my garage?
Bougainvilleas suffer “chill” injury at temperatures in the 30s, and the plants will be killed by sub-freezing weather. They need bright sunlight over the winter. Garages are usually too dark, and tropical plants that are kept there are really sluggish to recover come spring.
Dear Neil: I have a mature crape myrtle in my front yard that I have never had problems with. It gets full sun and has been blooming regularly all season. I noticed recently that the upper middle branches look like they’re being eaten by something. All the foliage of those branches is gone or has turned brown. I don’t know if this is worms or disease. Is there some way I can treat it?
This is usually due to the effects of sucking insects such as aphids or scale. They exude a sticky honeydew residue that allows sooty mold to grow on the leaf surfaces. The impacted leaves often fall prematurely, and we’ve seen a good bit of that across Texas this year. It’s not anything of a critical nature. The plant should be fine come spring. If that sounds like what might have attacked it this year, consider applying the systemic insecticide Imidacloprid in mid-May next year.
Dear Neil: I have a Chinese pistachio tree that appears to be dying. Its bark is coming off. What would cause this, and what can I do to save it? It’s about 10 years old.
Whatever caused the problem isn’t visible in the photo. My guess would be that it could be latent damage from last winter. A small percent of the state’s Chinese pistachios were hurt. Your photo shows cracks running parallel to the sides of the branch, indicative of such damage. But without seeing the rest of the top of the tree, that’s just a guess. You really can’t do much to help it at this point. Wait until spring to assess its chances, but get a certified arborist on site for a quicker read-out.
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