Dear Neil: Several years ago I had a tree guy remove some large oak branches that were touching our roof. The tree seems to have resented it, and now I need to prune it again. Do you have any advice?
A: My guess would be that the first person left stubs. The sprouts probably originated from those stubs, but of course, I can’t see through all the brush to know for sure. You can prune oaks now. The oak wilt season has abated. I would start removing the odd growth to see what is beneath it. Cut the old branches so that there is only a short piece of the branch collar. That will ensure that the tree will heal properly without further sprouts forming.
Dear Neil: I have a weed growing in my yard. It is very close to the ground. It has round leaves and shoots that go up about 14 inches with seeds on the end. I’ve tried pulling them up to no avail. Have I waited too long to use Dimension, Halts or Balan?
A: Those are pre-emergent herbicides, and they must be applied before weed seeds sprout — that is, before you can see the weeds themselves. I don’t know what weed you have, but obviously it’s at the other end of its life cycle. I’d suggest you take a sample of the entire plant to a Texas Certified Nursery Professional for identification and for recommendations of the best control. If it’s an annual weed you might get some control with a spring application. Always feel free to attach a photograph with your question in the future.
Dear Neil: Why are there ants on my crape myrtle? Do they hurt anything? What should I do?
A: The ants are there feeding off honeydew exudate from some other insect, probably crape myrtle aphids. The ants are harmless, but the honeydew will result in growth of sooty mold, an unattractive black fungus that will coat the leaves and stems. To control the sooty mold you need to control the aphids (or crape myrtle bark scale), and to do that it’s usually easiest to use a systemic insecticide as a soil drench in late spring.
Dear Neil: Some 20 years ago a friend gave me a start of English ivy to use as a groundcover beneath a large, old oak tree. It sat there for 19 years without doing much, but this year it suddenly grew up the trunk. I know that ivy can damage the surface of walls. Will it harm the tree’s trunk, too?
A: English ivy damages trees in two ways when it’s allowed to climb them. One is when it forms a canopy out and over the limbs. It can add weight to the branches, so that should ice or snow fall those limbs might break. Also, it shades the tree’s leaves and can deprive them of much-needed sunlight. But it will do nothing to damage the trunk. Nor does it do anything to masonry walls other than possibly trap dirt and debris behind it.
Dear Neil: We built our house 26 years ago. The nursery folks planted these crape myrtles probably too close to the house. Do we need to be concerned? They’re on the west side, and we really are grateful for their shade. Is there anything we should do? Should we have them taken out and have the stumps killed?
A: I’m not sure why people plant crape myrtles so close to houses. Perhaps they don’t read the descriptions saying that they’re going to develop large trunks and grow to be 20 to 30 feet tall. But we are where we are. I’d suggest just leaving them where they are and keeping their branches pruned well away from the root line. If you see any large surface roots starting to threaten the foundation, you can remove one or two of them per year, but do so in the fall (this time of year) when the plants’ need for water has lessened.
Dear Neil: I had a beautiful lawn that has now gone to this. At first I thought it was a disease, so I treated with a fungicide. Then I thought it might be chinch bugs. Even though I didn’t find any, I treated with Sevin. Still it got worse. What can I do? I have a large lawn, and I want to keep it looking good. My husband used to do it.
A: You’re not going to find them this late in the growing season, but I’m pretty sure the browned St. Augustine was indeed caused by chinch bugs. They show up when it’s really hot, and they’ll always be out in the sun. You’ve probably seen my many notes here about having to get down on your hands and knees to look for them on the surface of the soil. They’re BB-sized and black with irregular white diamonds on their wings. Watch for them in the same areas next summer. At this point all you need to do is keep the lawn moist the balance of the growing season and get it off to a good start next spring. Imidacloprid is one of the better controls for chinch bugs, usually applied in mid-summer when their damage first becomes evident. The grass will appear to be dry, but it won’t respond to irrigation.
Dear Neil: Each year the late summer bloom cycle of our roses-of-Sharon is ruined by small white insects and black mold. What is this, and how can we save the blooms?
A: The black mold is sooty mold, the same as we’ve talked about on crape myrtles, pecans and elsewhere. And the small white insects are aphids. To control the mold you need to control the aphids. Most insecticides will do that, but watch out for warnings on product labels about not using them on any members of the hibiscus clan (including rose-of-Sharon). The systemic insecticide Imidacloprid will do a good job of stopping aphids if applied several weeks ahead of time. Once blamed in part for bee colony collapse, that insecticide has been essentially cleared by many university entomologists who now feel that it’s more of a combination of assorted factors, not just insecticides. I’m also going to warn you that roses-of-Sharon are much better suited to parts of America where summers are more mild with more rainfall. I grow them in my own Texas landscape, and the spring bloom is always superior to what I get in the fall. However, when we get rain in August and September they can put on a good late show.
If you’d like Neil Sperry’s help with a plant question, drop him a note in care of The Eagle, P.O. Box 3000, Bryan, Texas 77805. Or email him at firstname.lastname@example.org.