Question and Answer – October 2011

Neil invites your questions to e-gardens. Please accompany your question with a photo, also with the city where you live, so that Neil can be more specific in his answer. If you don’t have a photo, Neil asks that you contact him via his radio programs. Normally, he addresses the 5 or 6 most pertinent questions, but there are more than that this month. We hope you gain from them.

Question: The waxleaf ligustrums in front of our house are getting too tall. Can we prune them back to about 3 feet this fall? K.R., Midlothian.

Answer: Early February would be much better. Fall pruning stimulates growth, which wouldn’t be good going into the winter. In all honesty, waxleaf ligustrums would grow to 10 or 12 feet tall if we didn’t prune them. Keeping that at 4 feet, as you’ve been doing, will eventually weaken them enough that they’ll not have the vigor they had as young plants. Cutting them back to 3 feet may be more than they can handle. However, if it works, you’ll be all set. If it doesn’t, it wouldn’t be that hard or expensive to replace them with a lower-maintenance, shorter shrub.

Question: We had many spider lilies when I moved into my house. Over the years, and due to a remodel, I only have a few bulbs left. How can I increase them? N.N., Plano.

Answer: They increase at their own will and at their own rate. If it were my bed, I’d leave the old bulbs alone, rather than disturbing the Asian jasmine groundcover. You could easily enough buy more and plant them in other parts of the bed. They’re fairly readily available.

Question: We built a new garage and our hackberries appear to be sick. Any advice? D.P., no city given.

Answer: This tree doesn’t look much different than most hackberries after this long and frightening summer. Water as you can, pray for rain and sit tight. I’ll be repeating this message several times through these questions and answers.

Question: This is the second Foster holly I’ve tried in this area. I originally had an arborvitae, but it got too tall. I’d like to use one of the newer arborvitaes if you think they are good. I want something with a pyramid shape. It’s shaded by a Shumard red oak, but it does get some afternoon sun. Suggestions? S., Arlington.

Answer: I’ve had tons of questions of concern (and one personally bad experience) with these new arborvitae. I wouldn’t use them if it were my home, especially in any amount of shade. In a heartbeat, I’d have Mary Nell or Oakland holly or one of the other "red" hollies in this spot. They come from the nursery already trained in pyramid form. That’s actually how they grow naturally. Plant it out far enough from the house that it gets light from all sides. Be really careful to hand-water it every 4 or 5 days during the fall and spring, as needed during the winter, and every 2 or 3 days next summer. They can dry out and die without your really realizing that they’re in distress. Looks like the Foster holly might have gotten too dry.

Question: We have three lacebark elms that the builder planted. This is the one in our back yard. We put a pool in last year, and I thought that might be why it had problems last year, but it happened again this year. What might be wrong with this one tree of the three? K.V., Frisco.

Answer: It’s hard to tell specifically from the photo. It still could certainly be root loss due to the pool. That sort of damage tends to hang around for several years. The problem would be magnified mightily by this summer’s hot, dry weather. Lacebarks are also susceptible to cotton root rot fungal soil disease. We have no control for it, and it probably would have killed the tree by now, so my vote stays with the probability of root loss from the digging.

 

Question: This red maple tree was planted two years ago. The trunk is about 3 inches in diameter. I’ve watered it faithfully every week. I have a 4-foot basin that I have filled, probably equivalent to a 2-inch rain. What could the problem be? D.G., Salado.

Answer: Any way we cut it, it’s still moisture stress. It could be leftover root damage from one time that it wasn’t watered soon enough. If it was balled-and-burlapped when you bought it, or if it had been dug and put into a container, it might have lost too many roots at that time. It could be damage to the trunk, perhaps from sunscald, that is impeding movement of water to the top of the tree. The hot, dry summer certainly didn’t help. "Moisture stress" is as close as I can get. I have to leave it up to you to refine the search. I will say that red maples do not like the hotter, drier parts of Texas, especially when confronted with alkaline or rocky soils. Much of that sounds familiar in the I-35 corridor, including Salado.

Question: What is causing the loss of pecans on my two 15-year-old trees? I don’t remember the varieties. In fact, one of the trees broke off when it was young, so it’s more of a pecan bush. D.L, St. Paul.

Answer: This is a fungal disease called pecan scab. It causes the pecans to fall prematurely, starting in August and extending into September. Your remedy is to spray with a fungicide, and you have to do so beginning in May. Every spray you make for pecan casebearers in late May and six weeks later, and for hickory shuckworm and pecan weevils in August should include a fungicide. Most of us opt, instead, to take those pecans we do get from our trees and not mess with all the spraying that commercial growers have to do. If you ever plant another pecan, the variety Caddo is notably resistant to this disease. It also produces high-quality fruit.

Question: I’m having trouble with my Chinese pistachio. I have seen many of these trees around town with the same issue. The bark is peeling, white spots are appearing on the limbs, and there are lots of berries with few leaves.  The leaves look healthy, just not many of them. I have been watering regularly this summer.  I wrapped the trunk with a white plastic wrap. Any other suggestions? B.G., Justin

Answer: This type of discoloration of bark can sometimes be a bad thing and at other times, nothing to worry about. I thought I’d better go to the pros, so as I have done in the past, I contacted my friends at Arborilogical Services in the DFW area. They’re just the best. Here is what Bryan White wrote back. Great information – thanks, Bryan!

“The shedding bark is a common function of the bark for this species.  As the bark tissue ages, it begins to peel naturally revealing younger smoother bark beneath.  The white spots on the bark is normal coloration and both issues pose no threat to the tree’s health.  The production of fruit (berries) requires a lot of energy and as a result the canopies will thin or shed foliage giving the appearance you have noticed.  Again this is common with this species, and in some cases I would recommend planting male Pistache over the females because of this very issue.  The white plastic is not needed and can be removed since it does not appear to be a sunscald issue.  Continue deep and infrequent soakings for your watering through the fall especially if we continue to stay dry.  Root feeding is also beneficial for maintaining good vigor and health with your trees.”

Question: About five years ago, my St. Augustine lawn developed brown patch fungus. It hit fast, and it spread quickly. By the time I figured it out, it was all over our large yard. From your website, I learned to spread sphagnum peat moss. Every year now, in August and September, I get 2-foot patches reappearing. Should I apply the peat moss? M.D., Weatherford.

Answer: Oh, my. There are three maladies mixed into this discussion. Take All Root Rot is a spring-only disease that is helped by the 1-inch layer of sphagnum peat moss. Brown patch is a non-fatal fall (October/November, rarely September) disease that kills the leaf blades only. What you’re showing in your photo, and what you’ve seen in August and early September is almost assuredly chinch bug damage. They can quickly kill big parts of St. Augustine. They will show up only in hot, sunny areas, and only in the summer. There is no reason to treat them now. Watch for their reappearance next summer. Click here for more information from my website.

Question: I had a lot of trouble getting grass to grow in this shaded area of our landscape, so I put in this walk. The left side of the walk gets at least 6 hours of sunlight. The right side only gets 2 or 3 hours. Any recommendations of plants to use? No name or city given.

Answer: That’s a handsome walk! If this were my area, I’d keep the landscape fairly simple and let the walk be the star of the show. I’d probably use golf ball- to tennis ball-sized river rock to fill two-thirds of the bed to the right. I’d probably plant a Carolina Jessamine, depending on where you live, just to give a little vertical relief. In my yard, I’d have several attractive glazed pots sitting on the bare ground to the right, and I’d fill them with caladiums, begonias or other color that would handle the lighting. I’d probably also have some of the less common aloes in pots. (I collect them.) You could use a low groundcover such as dwarf mondograss. On the left, I’d repeat the rock and the groundcover (in the shadier parts of the left bed), but I’d also plant perhaps three Carissa hollies or five to seven Harbour Dwarf nandinas as my shrubs. I’d certainly use a few brackets for wall pots, or perhaps one shelf for a few pots. Keep the plants small and the pots fairly light to avoid pulling the fence over at an angle, but use that vertical space to your advantage. You could also hang garden art there. An old window or piece of simple stained glass could be pretty.

Question: I love morning glories. This season, I’ve had plenty of buds every day, but they rarely open. They have not been fertilized, and they seem to be the only thing in our yard handling the heat well. But, no blooms. Is it heat-related? Suggestions? M.L., Lewisville.

Answer: It has to be the heat. They traditionally don’t bloom well until fall. You’re probably already seeing better blooms now.

Question: What type of weed is this? We normally see it around farm ponds. How can we control it in our yard? D.J., DFW area.

Answer: This is one of the sedges. You’ll notice the unusual flower heads that are typical of them. If you roll the plant’s stem between your index finger and thumb, you’ll notice that it’s triangular. Grasses are round. Image and Sedgehammer are both listed for control of sedges. Best time to treat would be late spring and summer.

Question: Is it normal for this plant’s flowers to bloom for only one day, and for new buds to come from June until fall? D.T., no city given.

Answer: Yes, and yes. Hardy hibiscus plants operate exactly that way. Great perennials.

Question: My tree is dying out due to the hot summer. What can I do to save it? C., Mesquite

Answer: This is a silver maple, and it looks like it’s growing in a somewhat challenging location with lots of concrete nearby. That’s a notoriously difficult place for trees to exist due to all the concrete that’s nearby. There appear to be a couple of branches that should be removed. Water it deeply every few weeks, and hope for the best. Their life expectancy in urban Texas settings is probably 20 or 30 years.

Question: A Knockout rose died in this bed after three years. This Sky Pencil holly only lived 10 days. What would grow here, where afternoon sun is really hot coming off the bricks? I reworked the soil each time. B.I., Fairview.

Answer: That’s probably not enough room for a rose, but if it lasted three years, the soil must be fine. It does look very chalky, however. Hopefully it has a lot of organic matter mixed in. My choice would be dwarf Burford hollies. They’re tall enough to conceal the downsprout and drain, and they can handle the heat. You’ll just have to be religious about watering them. I’ve seen a ton of them dry up and die from neglect this year. Rosemary might also be pretty, although it’s not absolutely winter-hardy. Be careful that the brown pipe pours onto the driveway, and that it doesn’t sink down and fill the small bed with rainfall runoff (when that decides to happen again).