Question and Answer – July 2012

If you’d like Neil’s input on a plant question at your place, drop him a note here at e-gardens. He answers those of greatest general reader interest. (No plant ID questions, please, since those are normally of concern only to the person sending the photo.) Since this is a visual medium, Neil answers only questions that are accompanied by a photo. Please give him your city, so that he can more accurately address your concerns. Click here to send Neil your photo and question. Watch here for Neil’s reply in the next issue of e-gardens.

Question: This photo is from a man with whom I work. He’s wondering what the elongated growths might be on his palm. I told him they looked like flowers forming, and that he might have edible dates. Advice? R.W., Garland.

Answer: Please tell your friend that you’re a pretty good horticulturist in your own right. Indeed, these are developing flowers. It’s doubtful that he’ll be dining off the fruit, however. Edible dates and coconuts are produced on more tropical species of palms that will grow only in areas with much warmer winters than Garland. Curiously, here is a link to an article on edible palm fruit. There are many other types, but no big superstars. Many seem to be acquired tastes.

Question: This Japanese maple has been in the ground for about five years. What might have happened to the trunk, and can the tree be saved? Could it be damage caused by rabbits chewing? We see them in our yard all the time. M.H., Plano.

Answer: The tree appears to be trying to heal itself, but it’s difficult to identify what might have caused the problem. All you can do at this point is to protect it from further damage, perhaps by putting a small and fairly inconspicuous fence of chicken wire a few inches out from the trunk. The tree is going to have to heal itself, and only time will tell if it will be able to do so. In the meantime, avoid high-nitrogen fertilizers, and keep it moist at all times (never wet for prolonged periods, and certainly never dry).

Question: What might be causing the leaves of our Chinese pistachio to turn brown around their edges? It happened last year, and it’s back. I did apply a product that was supposed to stop both insects and diseases. What are the spots on the trunks? G.V., Dallas area.

Answer: The spots on the trunks appear to be lichens. They’re a symbiotic growth of both lichens and algae, and they present no current danger to the tree, although they do seem to show up more often on wood that is in decline. However, they are not the cause of the issue. The leaves have scorched, and it’s hard to assign a cause to that. It’s due to moisture stress, and that can be from trunk damage from sunscald and borer invasion. It can also be from drought, also from weedkillers and fertilizers that have been misapplied. I would recommend having a certified arborist out to look at the tree.

Question: What might be wrong with my Japanese maple’s trunk? The bark appeared to be caving in. I removed the loose bark just before I took the photo. C.S., University Park.

Answer: The tree has suffered some type of injury in the past year or two, but it appears that it’s trying to heal across the wound. That’s a roll of new bark that’s forming across the open wound. Unless you see further reason for concern, I’d suggest just leaving it on its own. Do not apply pruning sealant.

Question: You’ll see, from my photo, clusters of what look like tiny green coneflower blooms where colorful flowers should be. What caused this? K.R., Carrollton.

Answer: This looks like an aberration of a coneflower bloom, almost as if the plant has mutated. I’ve grown coneflowers all of my life, and there are many types. Still, my answer may not hit the mark exactly. If this were in my garden, I would, out of curiosity, leave it one more year, to see what it does. If it turned out like this again, I’d be replacing it.

Question: I damaged my oak tree several years ago when I hit it with a trailer. It has not healed. In fact, the injury seems to be getting larger. What can we do? I don’t want to lose it. G.S., Denton.

Answer: It looks like there might be a roll of new bark trying to form, but it does also look like there is active decay within the wood. If this were my tree, I’d have a certified arborist look at it. The wound itself isn’t all that large, if you can just stop further decay and allow new bark to form across the open space. Plenty of big trees have voids and fissures within their wood, yet they still stand strong. This one needs a closer inspection.

Question: For the past two years, this weed has been taking over our back yard. We’ve tried hand-pulling, and we’ve tried the weed-blocking fabric, but it’s coming up everywhere. What can we do? N.L., Denton.

Answer: Any broadleafed weeds can be killed by the application of a herbicide containing 2,4-d. Independent nurseries have a brand or two that contain only 2,4-d, but most of the large national chains only sell combination products. The reason that is important is because 2,4-d is not active in the soil, but the other products are. So, if you’re treating within a landscape where there are trees and shrubs nearby, you’ll have to be concerned about their root systems. If you apply a 2,4-d product very carefully and specifically only to the weeds’ foliage, and if you spot-treat on a day when there is no wind to blow the herbicide, you can get good control. That would be my starting point. I think it will help you make good progress. Just don’t let your spray come in contact with flowers and vegetables. It will not harm your turfgrass, but you should still make your application late in the day.

Question: I have several trees that are suddenly dying. What would cause this, and how can I stop it?

Answer: Cotton root rot is a soil-borne fungus that kills plants very quickly, even after several years in a landscape. That’s what I expected your photos to show, but I’m not entirely sure. CRR could be responsible for the pear’s decline, but there also appears to be a huge amount of trunk damage, for whatever the reason. The other tree appears to be a willow, and if so, that could be the result of cottonwood borers. They riddle both cottonwoods and willows. I’m not sure you will turn the dieback around for either of these trees. It looks like it’s time to find suitable replacements. Work with an independent retail nursery, and ask a Texas Certified Nursery Professional to show you the best-adapted, most bulletproof plants that match your needs.

Question: I have a cherry laurel tree in my front yard. Its bark looks horrible, and a tree expert told me it would be dead within two years. What is causing it, and what can I do? D.M., Fort Worth.

Answer: Cherry laurels are landscaping shrubs that are sisters to peaches and plums, not to true laurels. I suspect that your tree has been hit by peach tree borers in its lower trunk. I agree with your arborist, although I doubt that this tree will make it two years. It’s really time for a replacement. Take the opportunity to remodel that part of your landscape with a new design.

Question: It appears that this tree might have iron deficiency on the one side. Do you agree? What will give the best control? M.W., no city given.

Answer: This was frustrating. I tried zooming in on the photo, so I could see the leaves better, but they pixelated more with each zoom, so I really couldn’t tell what kind of tree is involved. It would have helped to know where this tree is growing (what city), so that I would have known more about the soil. But, my answer probably would have been that you can apply iron and sulfur to the tree’s root zone to correct short-term iron deficiency. However, the tree will continue to get larger and larger, and it will cost you more and more money to keep it green. When I get inquiries from people in alkaline soil areas, and when iron deficiency is bothering their biggest trees, I normally tell them that they’re in for a long and expensive journey. It’s not the message you want to read, but you’ll probably eventually need to replace this tree. It probably wasn’t suited to your area in the first place. This is again a time to call a certified arborist.

Question: My Indian hawthorns are looking terrible. New growth has died, in spite of my application of a fungicide. Help, please. No name, no city given.

Answer: This is Entomosporium fungal leaf spot. That’s the fungus that has ruined redtip photinias all across America. In recent years, it’s also become a real issue for redtips’ cousins, Indian hawthorns. Unfortunately, there is absolutely no chemical control for this disease. Most of us who have hawthorns facing this fate have since replaced them with other, unrelated species. Again, sorry for the bleakness of the response.

Question: I have an oak tree with a powder beneath its bark, which is falling off. Does this look like oak wilt? S.C., Plano.

Answer: No, but it does look like Hypoxylon canker. Here is good information from the website of the people who do all of my tree work at our house (Arborilogical Services). I think it will shed good light on the subject.

Question: My driveway is lined along both sides by 20-year-old crape myrtles. They have begun to make it difficult to get down the driveway. How and when can I trim them? Should I do both sides, or just one? R.N., Aubrey.

Answer: Winter would definitely be the time to do this trimming, if you can possibly wait until then. Trim them from the bottoms up, removing entire branches back flush with the main trunks. These are spectacular plants, and if you’re patient, you can elevate their canopies by 2 or 3 feet, and do so in a way that won’t even be noticeable a few months later. Why don’t you hold off, then repost your question in December, along with these photos and 2 or 3 new photos. One photo should be from this same angle, then a couple of others showing individual trees. I will mark on one of the photos exactly where I would make the cut, and include it in my reply. However, I need to be able to see the branching a lot better than I can here. I can’t do that for everyone who asks about pruning specific plants, but when I see 30 crape myrtles looking this nice, they’re worth that extra effort.

Question: We lost a large pecan tree in this spot several years ago, and we decided to try growing peppers there. Now, we have this slime mold growing alongside them. Should we be concerned about the entire bed? J.R., McKinney.

Answer: This is one of the many types of saprophytic funguses. They live off decaying organic matter, and they are not harmful to plants unless they grow up and over them. You could try dusting sulfur as a treatment to stop its spread, but hot, dry weather will accomplish the same thing.

Question: What should I do about this split in the bark of my bald cypress tree? C.S., North Richland Hills.

Answer: This looks like it might have been a split that happened when the tree was hit by a gust of wind. The tree could be bolted with an all-thread rod inserted at right angles to the split. That would be a job for a certified arborist. The tree should heal on its own over time.

Question: I purchased hay to use as a mulch from a source I’ve used before. It appears that the hay was contaminated with weedkiller, although the supplier says he’s never used any. Will these plants recover? What can I do to counteract its effects? Are vegetables safe to eat, and will hummingbirds and butterflies be at risk? K.S., Smith County.

Answer: It would be really a stretch for there to be enough weedkiller on hay to cause all this damage, especially when a trusted supplier assures you that none was used. However, the symptoms are spot-on for that type of damage. Is there any chance that someone very near to your property might have been spraying on a windy day? If not, we’ll go with your assumption. There would be no threat to butterflies or hummingbirds. Probably there would be no risk to you in consuming vegetables, because if a plant is severely affected, it probably won’t have any fruit anyway. As for recovery, odds are against you. My bet is that you’ve already lost some of these plants by the time your note has gotten to me and this reply has been prepared. The plot should be safe for fall plantings over the next couple of months.

Question: Why did some segments of my blackberries turn brown this year? C.G., Sherman.

Answer: My guess would be that thrips could have been involved. However, to cover all bases, here is a bulletin written for Texas A&M by our friend Dr. George Ray McEachern. Scan down it to the "Problems" section.

Posted by Neil Sperry
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