It’s getting late, so kill those weeds before first freeze
Q: The compost that we bought and spread on our garden from a local source several years ago seemed to promote all sorts of weeds. Can we use a herbicide on the garden now to get rid of the weeds before we take another load of compost for this year and rototill it in prior to spring planting?
A: That’s a good plan for fall garden preparation, but in all honesty, it would have been better if you could have done it in October. It will work as long as the weedkiller (a glyphosate-only type would be best) has two weeks to kill the weeds prior to the first killing freeze. That’s why an earlier date is better — you want to be able to kill weeds like Bermuda grass, Johnson grass and other perennial grasses before the first freeze turns them to chaff. But give it a try. It will still help unless they’re all already brown.
Q: I have read that the tall shoots of my azaleas should have been cut back after their spring bloom, but obviously, I didn’t get the job done. Should I do it now, or will I be removing next spring’s flowers?
A:
It appears you have one of the repeat-blooming varieties that has two or three bloom cycles per year. If so, it would be best to prune the plants lightly after each flowering round.
Looking at your photo, I would use loppers to remove that one woody stem in the center back into the crown of the foliage so you couldn’t see the cut. I might do the same with the dark green stem to its
right. The rest of the branches are smaller and younger, and I would just do some selective tip-pruning on them.
After each cut, step back and see how the planting looks before you make any additional cut. You can always remove a branch or twig later. You can never put it back.
Blow the grass clippings off the base of the periwinkle and azalea leaves to prevent any kind of decay from starting up.
Q: I own a ranch in Frio County. I built a new house there in September 2020 and had a number or red oak
trees (75-gallon) and cedar elms put into the irrigated landscape. I was afraid the cold of February 2021 might have harmed them, but they budded out and looked great.
By September 2021 the leaves started turning brown around the edges, and then went completely brown and fell off. A few weeks later, they regrew. The same thing happened this past summer. The trunks have been wrapped to protect them, and I’ve had the tree well irrigation running four times per week to keep them watered. The ph of the soil is neutral and the soil is a sandy loam. What can I do that I haven’t described?
A: It looks like a lovely setting. Let me give this my best shot.
My first concern is always to be sure the reader actually got true Shumard red oaks (the ones that are best suited to conditions in the western 80 percent of Texas). Too often, when large container-grown trees are planted, they have been shipped in from East Coast growers who tend to use other extremely similar species or hybrids that may or may not be true Shumards. Those varieties often are quick to show iron deficiency (yellowed leaves, dark green veins, most prominent on newest growth) in the alkaline soils near and west of I-35 across Texas.
You are obviously far west of I-35, but you did state that your soil’s ph is neutral. I hope you have verified that through your county Extension office, because the trees in two of your photos certainly look like they’re showing signs of advanced iron chlorosis.
Just for the record, when that appears on newly planted trees that were bought as Shumard red oaks, I recommend that customers go back to the nursery immediately. You cannot add enough iron to overcome this shortage on a long-term basis. You can do so initially, but by the time the tree quadruples in size, it becomes physically and fiscally impossible to do so.
So, that is one thought. I also see edge burn on some of the leaves. That suggests moisture stress, and that could come from too little water at critical times, but it could also come from excessive mineral salts in the water. Those salts accumulate and end up damaging the roots. Your county Agrilife
Extension office would be able to help you.
Finally, I can’t tell how far up on the trunk the tree wraps extend. Hopefully it’s to the lowest branches, but it looks to me like it may not be quite that high. There could be some sunscald already taking place in the trunks of some of the trees. I can’t tell.
It’s probably time to have a chat with the nursery that supplied these trees or the people who planted them. It may be one and the same. Somewhere in there you should be able to discover some answers. Good luck!
Q: I read your answer about leaving St. Augustine tall during the winter and that it would not be beneficial. Our issue is that a mower set to 3 inches would literally scalp our lawn. Right now it’s at 5 1/2 inches so that we can still have green showing. Have you ever heard of that?
A:
No. Not in 65 years of tending St. Augustine lawns! Here in Texas, we have two common turfgrasses, St. Augustine and Bermuda grass. (I know I’m restating the obvious.) Both are creeping grasses that produce runners. The more runners, the denser the turf will be (a good thing).
When we start to mow grass taller than recommended, the blade growth becomes vertical, as it were, “reaching for light.” Runner production is greatly reduced (a bad thing). Your chance to lower the height will come at the end of winter, when the grass is likely to be browned from the cold. That would be the time to drop the blade down to get things back to a more normal height.