GARDENER'S MAILBAG: Tree options less susceptible to disease?

By Neil Sperry
Special to the Herald Democrat

Dear Neil: I lost a Leyland cypress to Seiridium canker and now I have an Arizona cypress that is showing signs of the same. You suggested eastern red cedar as the best replacement for the Leyland cypress. Do you have a good option for the Arizona cypresses? I actually have seven, so I fear that I’ll eventually be replacing them all.

That disease has really cut into our choices in conifers. I hate it that we’ve lost Arizona cypresses from our planting lists. They’re handsome trees, but they have become quite susceptible. Many of our other junipers have issues with Phomopsis and other diseases, so they aren’t much better. Eastern red cedars are Juniperus virginiana, and that species seems to be resistant or immune. Some of the cultivars might work. I’m thinking of the old variety ‘Burki’ with its blue-gray summer needles and plum-reddish winter color. I’ve grown it a couple of times and had fair to good results with it. Be careful of others, however, because some of the selections out of that species are groundcovers, and others are vase-shaped shrubs, not the look that you’re wanting. It might be better to switch over to some other type of small evergreen tree such as Teddy Bear or Little Gem magnolias or tree-form hollies.

Dear Neil: My rosemary plant had quite a lot of new growth this spring, but now it seems to have stalled out. Can I simply trim off the branches that have no growth?

Rosemary with freeze damage

Yes. In fact, your plant needs to be pruned severely, and that trimming needs to be followed up with an application of an all-nitrogen lawn fertilizer (no weedkiller included) to stimulate new stem and leaf growth. Hopefully it will rebound quickly this late summer and into the fall. Otherwise you may want to set out a new plant next spring. This past winter was very unkind to many plants in Texas, rosemary included.

Dear Neil: I can’t figure out what is happening to my beautyberry. It did the same thing last year. One branch wilted and turned brown and then the branch beneath it did the same thing. You can see that happening in my photograph. It gets about seven hours of sunlight daily. Could this be too much or too little water?

Beautyberry dead branch

If it were getting too much or too little water, the entire plant would be impacted uniformly because the entire root system would be damaged. Is there any chance that the branch on that side has been broken? You might check closely for that. That is about as much sun as you would want to give beautyberry in Texas, especially when it’s growing right above a reflective stone surface. The rest of your plant looks just a little bit wilted, too. Finally, to be entirely base about things, do you have a male dog?

Dear Neil: A friend gave me bluebonnet seeds this past spring and told me to plant them in early fall so that they could come up in October. They are already starting to grow, as you can see in my photo. Is it too early to plant this into the garden, or should I leave it in the pot?

Bluebonnet seedling

Go ahead and plant it right away. You’ll want to trim away the weeds that are growing alongside it. You probably have several other bluebonnet plants that are going to develop as well. They will be fine. Plant them in the bed where they’ll have ample room and full sunlight.

Dear Neil: I nailed a metal cat to the trunk of my cedar elm tree several years ago, and now the tree has grown around its feet. How damaging is that to the tree? Is it possible to remove it without doing damage to the tree?

Trees grow around things that we have hung on them all the time. If you Google the key words “bicycle in tree Washington” you’ll see a photograph of a tree that has encased an old bicycle in one of their parks in the Northwest. If you want to remove the cat, use a small and very sharp chisel and take tiny pieces of bark away until you free it. Keep the wound as small as possible.

Dear Neil: What is causing the spots on my St. Augustine blades? How can I eliminate them?

Gray leaf spot St Augustine

That’s the fungus gray leaf spot. It most commonly follows application of nitrogen during the hot summer weather. It is a disease that can be controlled by application of either Daconil or Azoxystrobin fungicides to the turf. However, the best long-term solution is to avoid application of nitrogen between June 15 and September 1.

Dear Neil: Why would the bermudagrass in my backyard be as brown as January? Bermuda in the front yard looks normal. St. Augustine in the backyard looks normal. Why the difference?

I’ve had reports of army worms in various parts of Texas already. They strip bermudagrass of its green blades. This is the time of year that they are often active, although yours may already have run their life cycle and have pupated into moths. You often will see birds feeding in lawns where they are active. The larvae can be controlled with almost any general-purpose insecticide. The other possibilities are the water mold funguses Pythium or Phytopthora. They show up in turf that is excessively wet or over-fed.

Dear Neil: What would be causing the spots on the leaves of my Pothos? It was given to me as a gift years ago by a student following my first year of teaching. I want to keep it healthy.

Pothos with leaf spot

It is not insect- or disease-related. I’ve grown Pothos all of my life, and I have never seen a pest bother it. This looks like some kind of root damage or salt burn to the leaves. Be sure its pot has excellent drainage and be certain that the potting soil drains well each time that you water the plant. That will leach out accumulations of fertilizer or other mineral salts.

Have a question you’d like Neil to consider? Mail it to him in care of this newspaper or e-mail him at mailbag@sperrygardens.com. Neil regrets that he cannot reply to questions individually.