GARDENER'S MAILBAG: What insect is eating my oak tree?
Dear Neil: I have an issue with some type of insect eating my red oak tree. (Please see photos attached.) What type of insecticide would control them?
This is not about an insect. I don’t know why the tree would have been pruned the way it has been. However, the severe topping of the tree has led to decay through the heartwood of the trunk. Borers have then moved into the trunk over the years and devoured the wood. Feel free to get the second opinion of a certified arborist. I am fearful that this tree could fall once it leafs out. The canopy will catch the prevailing winds, and there may not be enough strength left in the trunk to support it all. I believe it’s time to have it taken down and to find a replacement tree.
Dear Neil: We found this damage to the trunk of our cedar elm tree after the great freeze. Can you tell us what happened?
That’s very striking to say the least. It really doesn’t even look like a cedar elm trunk. If anything, it looks more like a lacebark elm. If there were anything out of the ordinary that happened to it, it would probably have been borers just beneath the bark. They might have tunneled around for a long period of time (not just since the freeze). But again, this really looks more like the normal exfoliating bark patterns of a lacebark elm. I can’t see enough of the tree to tell for sure.
Dear Neil: I am planning to add some gardens and plants to my mom’s backyard along her fence line. The section is in a low spot that stands in water for a day or two after significant rains. Are there any plants that will withstand those conditions, or if it’s easier, are there any that we should specifically avoid? I was thinking of removing the grass and adding some gravel or small rocks about 3 or 4 feet from the fence.
Adding gravel to that setting would not improve drainage any more than it would help a plugged-up bathtub drain. And choosing plants that specifically can withstand boggy soil is risky, just as you don’t want to use plants that are intolerant of standing water, even for short periods of time. The best solution would be to create an extended berm of raised garden soil. Bring in sandy loam topsoil and include several inches of organic matter (compost, pine bark mulch, rotted manure, sphagnum peat, etc.) with it as you rototill to a depth of 10 or 12 inches. That way, excessive rainfall will drain away quickly. You can always add water. It is much more difficult to subtract it. By doing it this way, you can plant almost anything you wish.
Dear Neil: Is there any chance that waxleaf ligustrums that have lost all of their leaves due to the cold will come back from their bare stems?
Sadly, it does not appear so. Even if they would, they would be so weak that you wouldn’t be satisfied with their recovery. They were hurt across big parts of Texas this time around.
Dear Neil: I planted new St. Augustine sod last October. Now it is full of bur clover. All the products I see listed for killing clover will also kill St. Augustine. What can I do?
Use a broadleafed weedkiller (containing 2,4-D, perhaps with only that active ingredient). Apply the spray with a tank sprayer and adjust the nozzle so it applies fairly small droplets. That will allow you to coat the leaves of the clover without getting it all over the entire lawn. Spray on a day when temperatures will be below 85F and you shouldn’t have any problems. I’ve done this on my own lawn many times without any issues with my St. Augustine.
Dear Neil: What is this insect on my holly, and how do I control it?
This is a scale insect, similar to what you will often see on euonymus shrubs. You can keep it in check with use of Imidacloprid systemic insecticide, both as a spray and as a soil drench. You would also want to apply a dormant oil spray in late January. The oil breaks down the protective waxy outer covering of the insects and exposes them to freezing weather. Note: scale insects usually do not fall off the host plants when they die. Crush them to see if they’re still living. If they still retain fluid you will need to keep treating.
Dear Neil: What are the chances my loquat can be saved? All of its leaves turned brown after the freeze.
Very, very tiny. It’s extremely rare for them to freeze like they did this February and still survive. If you haven’t seen vigorous new growth by now, you’re probably not going to.
Dear Neil: Several years ago I replaced a dying redtip photinia hedge with loropetalum (Chinese fringeflower). Sadly, this year, the cold got them, too. What would you suggest as a good replacement screening plant?
I would suggest Willowleaf (8 ft.), Oakland (10 ft.) or Nellie R. Stevens (14-16 ft.) hollies. They came through the cold unscathed. However, because of that, people are rushing to plant them. You may have a difficult time finding good-sized plants in your favorite nurseries for a while.
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