Question and Answer – December 2012

This is one of the most popular features of e-gardens, as Neil addresses questions of greatest reader interest. (Note that plant IDs are generally of importance only to the person with the plant.) He requests a photo accompany all questions we use here, and it would help him if you would also list the city in which you garden so that he can tailor the answer more precisely to your part of the state. Here is a link via which you can send him your question and photograph.

Those simple factors out of the way, here are this month’s questions and Neil’s answers.

Question: Our Aloe vera plant has bloomed this past year and two years ago. The people from whom we obtained the plant, and friends with whom we have shared plants have not had flowers. Is this common for this plant, or are we just fortunate to have this one? D.N., no city given.

Answer: Aloe vera blooms rather reliably when it is grown as a single plant, as opposed to a clump of smaller plants. There are hundreds of species of aloes in cultivation, and many of them are well known for their flowers. If you want to promote blooming, remove the side shoots ("pups") and keep encouraging the mother plant to grow larger.

Question: I have two Natchez crape myrtles that were doing great until mid-summer, when the new growth started having the odd patterns you see in the photo. I have not seen any insects. I was told it was a fungus, and I sprayed with a fungicide, but they continued to look like this. Is it a fungus? What can I do next year to keep it from coming back? S.T., Fort Worth.

Answer: In all of my years of dealing with crape myrtles, I have not seen this problem (at least, not that I can tell). It is very unlikely that it’s a fungus, because the mottling is so regularly spaced between the veins. Some might say it was iron deficiency, but it certainly doesn’t follow the normal pattern for that. I do suspect, however, that it is nutritional. My guess would be that a high-nitrogen fertilizer that also included a trace elements package would probably help. I would feed it for the first time about the middle of March, as the buds are beginning to appear. I’m sorry not to have a better answer. Perhaps someone else will write with a more precise suggestion.

Question: What would cause these small mounds in my zoysia lawn? I scrape them away, and there is a bald spot left where they were, but I find no critters. What would do this? J.Y., San Antonio.

Answer: They’re rather robust for earthworm castings, but that’s the common source of small mounds of coarsely grained soil. Other than that, it would probably be a large beetle of some sort. But, the main operative is that if you’re seeing no damage, there is no real call to action. Please dig around just a bit more. Perhaps you can find us a few more clues.

Question: This unusual mushroom-type growth has appeared in my lawn. I can’t seem to get rid of them. I pull them up, and more appear to take their place. Are they poisonous to dogs? What can I do to eliminate them? G.E., no city given.

Answer: These are quite similar to mushrooms. They are one of many types of saprophytic funguses. That means that they’re living off decaying organic matter such as tree roots or grass clippings. They are not parasitic to the lawn or other landscape plants. Dusting sulfur probably would help eliminate them, but they will also probably run their course before long. Dogs typically do not bother these funguses.

Question: I can’t get rid of the weed in the photo I’ve attached. I prefer using vinegar to kill weeds, but this one won’t go away. What should I do? J.J., no city given.

Answer: This is roadside aster, and this has been a banner year for it. It’s a weed of neglect, meaning that it will show up in the parts of our lawns where we have the most difficulty maintaining our turf. That’s usually out by the street or back in the alley. The best thing to do for it is to ramp up the care you give your turfgrass. You could apply a Gallery pre-emergent herbicide if you wished, or you could spray it with a broadleafed weedkiller during the summer, before it starts blooming again. I am not an advocate of vinegar as a herbicide. In fact, I will not accept it as an advertised product, because I do not think it will work efficiently. The legal labels affixed to the vinegar products I have seen do not give details of how to apply it, what to do if things go wrong, etc. Separate sheets of paper lying on the counter beside the bottles make those claims. My opinion is that that is skirting the regulations.

Question: I have a Brown Turkey fig that has outgrown its space (again). I have cut it completely to the ground once, and I intend to do so again in January unless you have other options for me. J., Belton.

Answer: The only good options would be either to move it to a more spacious setting or to take it out altogether. Figs should be planted where they can grow to full size (15 to 20 ft. tall and wide). They do not belong in small landscapes or against houses. When you prune figs heavily, and when they suffer freeze damage in very cold winters, they typically don’t bear fruit again for several years as they regrow. In all honesty, you’re merely postponing the inevitable if you continue to trim it. (Comment offered only in the spirit of saving you long-term frustration.)

Question: This is a seedling tree that I’m considering moving to the west side of my house, where it can give me shade. Is it worth moving? I don’t know what type of tree it is. Mrs. C.K., Metroplex.

Answer: I normally don’t tackle plant IDs here, but this appears to be a tree-of-heaven, Ailanthus altissima. Do a web search for "photo Ailanthus altissima" and compare them to your photo. If that’s what you have, it probably would not be a tree that I would bother replanting.

Question: What is this weed that is all through my St. Augustine lawn? I have tried pulling it up, but the taproot is very deep, and I never seem to get it all. What can I do? S.O., no city given.

Answer: This is prostrate knotweed, and it’s a tough one to eliminate. Broadleafed weedkillers will do a reasonable job (at best). It is usually found in lawns where the soils are compacted, also where the grass is somewhat neglected. Here is information from North Carolina State University.

Question: My green-leafed agave is putting up a flower stalk from a pup (not from the big, older plant). A gray-leafed form did the same thing in August. Is this uncommon? Will the flowering plant die? J.N., Denton County.

Answer: It’s quite unusual. The reason the gray-leafed type (Agave americanan) is called "century plant" is because it must grow for many years (usually 10 to 15) to become mature enough to flower. Small plants rarely do so. I would guess that the stresses of the past couple of summers may have caused your two plants to bolt prematurely into bloom. Yes, the flowering plants will die after the stalks have withered.

Question: I have two beds, each about 10 square feet, filled with spider lily bulbs. The beds get full sun until noon all year long. I only get 12 to 15 flowers per bed each year. What can I do to encourage more blooms? The beds are six years old. C., The Colony.

Answer: You might try digging and dividing the bulbs, to give them more room. Mid- to late summer would be ideal. They look rather crowded. My life’s experiences with spider lilies have been that they do bloom better some years than others. I’ve also found that they need to become established for a couple of years before you’ll see much in the way of flowers.

Question: This weed has invaded my ajuga bed and also the St. Augustine. What can I use to eliminate it that won’t hurt the turf or the ajuga? S.B., Arlington.

Answer: This is dichondra. It’s a very common, low-growing weed that defies pulling, because its stems break apart and reroot into the ground. You can use a broadleafed weedkiller (containing 2,4-D) to control it in the lawn, but you’ll have to be extremely careful near ajuga. What kills the dichondra will also kill ajuga. I would use a foam rubber paintbrush to apply it specifically to the leaves of the weed. Do not spray it near the ajuga. You could try it on a warm, dry day soon, or you can wait until spring. However, it grows fairly rapidly in the late winter, so you probably should begin your control program now.

Question: Our neighbor’s arborist removed two branches from my pecan. They extended over her roof, and they were raining pecans all night and keeping her awake. Will the green pecans I picked off them eventually ripen? Also, what is the large oak whose acorns are on the left side of the photo? J.G., North Dallas.

Answer: Pecans do not continue to ripen once they are removed from the tree. Pears will continue to ripen, but most other fruit and nut trees do not. The acorns are from bur oak (Quercus macrocarpa). It’s a great landscape tree.

Posted by Neil Sperry
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