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TEXAS GARDENING: Live oak thinning may be due to oak leaf blister

TEXAS GARDENING: Live oak thinning may be due to oak leaf blister

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Dear Neil: This big old live oak in our backyard seems to be thinning. There are a lot of leaves on the ground. We do not believe it is oak wilt. Should we call an arborist? What else could it be?

A: It would always be a good idea to get a certified arborist on site. He or she might detect a problem that we can’t even see. One thing that comes to mind is oak leaf blister. I had scores of samples sent to me and photographs emailed to me this past spring, and it continues currently. You might search that topic online and see if your leaves look similar. That particular fungus is not especially threatening, but it has certainly caused a large amount of leaf drop.


Dear Neil: We share a red-tip photinia with our neighbors. This year, its flowers were less than spectacular, and since then its leaves have started to turn brown. Is there anything that can be done to save it?

A: I can’t see the leaves well enough to tell if Entomosporium fungal leaf spot is involved. It causes maroon “freckles” and then loss of dark green color to the leaves. Best I can tell, this really doesn’t look like that. This looks more like cotton root rot. Sadly, both are fatal problems. If you are sure that you’re watering adequately, about all you can do is wait and see.


Dear Neil: We planted three yellow yuccas this past spring. I’m wondering if there is a problem, or if it just takes them a while to get established. They’re in full sun. Water from the pool does not get splashed on them. Any suggestions?

A: What you have planted is the yellow form of red yucca. It’s not a true yucca, but a great xeric plant botanically called Hesperaloe parviflora. “Yellow” Hesperaloes are slow to spread, so commercial landscapers buy fairly large plants and set them somewhat close together. I do note the one plant has a drain right beside it. Hopefully that’s not because of standing water in its vicinity. These will do well for you.


Dear Neil: Our Texas persimmon tree looks like it is in terrible trouble. The leaves have bumps all over them, and the Asian jasmine beneath it is also looking bad. Any suggestions?

A: I’ll deal with the two things separately. The persimmon tree has galls caused by a small mite. They’re primarily cosmetic, and there isn’t anything you can do about them now anyway. You may not see them again for years. As for the jasmine, I suspect that it simply got too dry one time. It will probably bounce back.


Dear Neil: We have a huge overgrowth of vines running rampant on our property. How can we eliminate them without doing damage to the trees? Would Round Up work?

A: The original Round Up was a grass killer that contained the active ingredient glyphosate. As such it was very effective on grasses, but not as dependable on broadleafed weeds like you have. And, because of the trees, you would not want to use a broadleafed weedkiller spray that might damage the trees. If this were my property, I would probably use a power brush cutter of some sort to trim the vines away one section at a time. I would trim a bit and then use a strong garden rake to pull it loose before trimming more. It will take less time than you expect.


Dear Neil: I read your story about sky pencil holly. I had professional landscaping done at my home, and the sky pencils that they planted did not survive. What other options would you suggest?

A: Sky pencil hollies must have acidic soil to thrive. Scarlet’s peak yaupon hollies are much better adapted to the entire state. They are also decidedly columnar. Do look into Oakland hollies. They are upright as well, and I think they’re a lot easier to maintain.


Dear Neil: I have a 35-year-old crape myrtle that has always had fabulous blooms. This year, however, it has bloomed sluggishly. The few bloom clusters opened, but most of the petals dropped. It’s been very hot and dry this year, but that has happened in years past and they still bloomed. There is a live oak nearby. Perhaps it’s now casting too much shade. Is there a fertilizer I should be applying?

A: Crape myrtles need full or nearly full sun to bloom to maximum capacity. If it gets shade before mid-afternoon, that is likely the problem. Did you notice if it suffered any freeze damage last winter? Many crape myrtles in Texas were hurt by the cold of the first killing freeze last fall and were lethargic bloomers this year. Keep watering it regularly, and apply an all-nitrogen plant food monthly during the growing season.


Dear Neil: I planted four dwarf yaupon hollies two years ago and lost several of them in spite of my drip irrigation. I have replanted, and they are still having trouble. Is this a water issue? Too little light? Some kind of disease?

A: This is a lack of water at a critical time. I am just not at all an advocate of drip irrigation for new plants. Too often it fails them. Dwarf yaupons do not have disease problems, and they handle shade quite well. (They may grow a bit lanky, but they thrive.) I’ve seen hundreds of them that look just like this after they got marginally too dry for a short period of time. This plant should bounce back, although you will need to trim away the dead stems.


If you’d like Neil Sperry’s help with a plant question, drop him a note in care of The Eagle, P.O. Box 3000, Bryan, Texas 77805. Or email him at mailbag@sperrygardens.com.

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