Redbud tree causes concern, leaves impact groundcover
Q: My eastern redbud, albeit, leaning, seems to be healthy and has bloomed for several years. I noticed in the spring that it has an area that is moist and weeping on its trunk. Should I be concerned enough to seek a diagnosis and treatment? A: Yes. However, it looks like there is a significant crack developing in the trunk that will soon cause the tree to split. The seepage is from decay within that cracked area. You could certainly have a certified arborist examine the tree. I guess it is possible that it could be bolted back together and perhaps even cabled higher up in the branches, but it doesn’t look like it will ever heal properly. But that is just my assessment looking at it from the one angle. Incidentally, the flaky growths on the trunk are lichens. They are basically harmless to the tree, although their presence in these numbers indicates that the tree is not sloughing off old bark as rapidly as it should be.
Q: Which is better: mechanical or liquid aeration of the soil?
A:
Be certain that aeration is actually needed. Heavy clay soils are not, on their own, bad things. Clay has massive amounts of surface area to collect and hold water and nutrients. Most plants will tolerate them, especially if we amend them with organic matter and expanded shale prior to planting. On the other hand, if we have accumulations of thatch, or if there is excessive compaction due to pedestrian or vehicular traffic mechanical aeration can help. Use a “core” aerator that physically pulls small plugs of soil or thatch up out of the ground and drops them onto the top of the lawn. That will allow air, water and nutrients into the root zone. It’s
not a process that is commonly needed, but it’s available if there is a problem. Finally, just a quick comment relative to liquid aeration products as well as those that claim to “open soils” or “activate enzymes” and “stimulate microbes.” In my opinion, those are ultimately vague terms that I have never seen backed up by legitimate university research. Be very careful in how you spend your money. Texas requires no proof of those claims before such products can be sold here.
Q: I have Asian jasmine as groundcover instead of a grass yard. My live oak tree is dropping lots of leaves into the jasmine. Can the large number of leaves keep the jasmine from filling in? It seems to be sparse in spots.
A:
Live oak leaves pack tightly and could hinder the normal flow of water into the soil. They also are very slow to decay. I would suggest blowing out as
many as you can, stopping just short of damaging your groundcover with the force of the wind. Collect the leaves and run them through your mower, then use them as a mulch beneath shrubs, or put them in the compost pile. Yes, I think they could slow the rate of coverage of your Asian jasmine.
Q: I have a lovely Texas mountain laurel that we planted 10 years ago. It has done very well, but now my daughter tells me that she has read that all parts of the plant are poisonous, even simply by touching them. Could it be the other mountain laurel? I’ve never had any problem with it.
A:
Texas mountain laurel (Sophora secundiflora), also known as mescal bean, does have toxic tendencies, although North Carolina State University’s website says it has “low severity poison characteristics.” Its hard-shelled seeds contain the highly poisonous alkaloid
called sophorine which is cited as a narcotic and hallucinogen. I’ve been around this plant most of my life and I’ve never known a problem. I certainly wouldn’t worry too much were I in your shoes. I would not rush to take yours out!
To have answered you completely, eastern mountain laurel (Kalmia latifolia) is more commonly known and seen in garden references. It is the state flower of Connecticut and Pennsylvania. It requires moist, acidic soils. It’s uncommon in Texas. According to the website of the Missouri Botanical Gardens, all parts of it are poisonous if ingested.
Q: I have a garden in South Texas where I planted an anacua tree three years ago. I water it and fertilize it, but it has not bloomed for those three years. What can I do to help it bloom?
A:
It sounds like you planted it shortly before the record cold of February 2021, so that is assuredly playing a big part in its slow development. It also looks like it has needed water and nitrogen to promote more vigorous growth.
Q: I’ve been a reader of your column for a long time. I know you addressed germinating Texas mountain laurel seeds some time ago, but I haven’t been able to find it. Can you give me the date, or a copy of that article?
A:
It’s a lot easier just to repeat the details. Texas mountain laurels have very hard seed coats (the outer red portion). If you like to think of it this way, that’s nature’s means of ensuring that all the mountain laurel seeds don’t germinate the first time it rains. They germinate over an extended period of months and years in nature.
However, when we need faster, more uniform germination we can speed them along by holding their seeds in a pair of pliers while we file through the red seed coat with a small, three-cornered file. Go just through the red seed coat and stop when you see beige filings pouring out. Those are from the seed leaves. At that point, put the seeds into a bucket of water overnight. Plant them the next morning into 4-inch pots with potting soil. Keep them moist and warm and they will germinate within two to four weeks.