Q: I have a Mexican bird of paradise that was planted five years ago that suddenly died. It had flourished until now. I pulled out the plant and sent you some pictures of the dead plant, girdling or circling roots and borers that I found in the center of the stem that probably killed it.
A: I read your question and looked at the pictures with quite a bit of interest. This is the first time I have heard of flatheaded borers infesting Mexican bird of paradise. These are the same borers that attack fruit trees and landscape plants.
Flatheaded borers, when they are young, feed just under the bark of the tree in the living vascular tissue. The center of woody plants is not living, so they stay feeding where they can find water and nutrients. Essentially, they tunnel just under the bark and parallel with it in a random pattern.
It is here that these larvae find the most nourishment for growth. When they get larger and ready to pupate or turn into the winged adult beetle, they burrow toward the center of the plant, where there is not much nourishment. But this area does offer them protection.
Here they begin their metamorphosis until they finally emerge as the adult beetle, which flies away and mates. The female lays eggs on the outer surface of susceptible plants.
It’s not unusual to see some tunneling toward the woody center of limbs or stems, or at least inside the wood of some plants.
Girdling roots, larger roots that grow in circles, occur in plants when they are very young at the nursery. The roots of these plants are crammed into small nursery containers, where they start growing in circles. They are then moved to larger containers, where they continue to grow in circles. That cycle continues when they are planted in the landscape.
Gently remove plants from their containers and check for girdling roots before purchasing them. This is the only way you would know if they are girdling or not.
Q: Would it be safe to plant a flowering plum tree in September or October, or should I wait until spring?
A: I wouldn’t. I would wait until maximum daytime temperatures dropped down to the low 90s or high 80s. In Las Vegas, that would probably be late September or early October. I would be comfortable planting trees until about Nov. 1.
There are plants that like to be put in the ground when it’s hot. Palms are an example. They don’t like to be planted when it’s cold.
The cutoff for planting hybrid Bermuda grass is the end of July. It needs about two months of hot weather to knit into the soil.
Actually, fall is an ideal time to plant if you can find the plants you want. Fall planting gives you two times when the weather is nice: fall and the following spring.
If you find a tree on sale now, it will take a lot of diligence to keep it from getting damaged because of the heat. I would put it on the east side of the building and make sure it gets protection from the late afternoon sun. Or put it in filtered light.
If it’s in a 5-gallon container, I would water it twice each day; once in the morning before it gets hot and the second time in the afternoon. Don’t let sunlight directly on the container. The surface temperature will heat up to about 160 F in just a few minutes. It can kill half the roots inside the container facing the sun.
Get a second container the same size. Put some large rocks in the bottom, and put the containerized plant inside of it. It’s called double potting. That will help keep the heat off it.
Q: I have a dwarf peach tree that was about a foot when I planted it last year. It has grown about 6 inches now. When can I prune it so it doesn’t grow taller than me? I am only 4 feet 10 inches, and I don’t want it to grow tall because I’m going to net it.
A: I want to mention a couple of things regarding your question. First, perhaps you mean it is a miniature peach and not a dwarf. Sometimes miniatures are also called genetic dwarf trees. To remove confusion, let’s call the genetic dwarf trees “miniatures.”
Sometimes the nursery trade calls peach trees grafted on certain types of rootstocks dwarf. It’s true they are a little smaller because of these rootstocks, but not much. The term dwarf is more of a marketing ploy as far as peaches go.
Genetic dwarf or miniatures are truly much smaller than the so-called dwarfs. They also grow differently and produce their fruit on branches differently. They are truly dwarf compared to standard-sized peach trees and the other so-called dwarfs.
If you have a genetic dwarf or miniature peach, then it will be pruned much differently from other peaches. You want limbs coming from the trunk as low as possible. Bend these limbs toward the ground, like they have a fruit load on them. See if the fruit might touch the ground.
If the fruit might touch the ground, consider removing the limb or at least cutting it back. Cutting it back might thicken and strengthen the branch and give the fruit more support so it doesn’t touch the ground.
At this point in its life, you just want it to grow. If it has side branches coming from the trunk at around the height of your knee, then it is doing it all on its own. If it’s a single stick and thick as your little finger, cut it at knee height. This cut will cause this solitary stem to start branching.
Secondly, why are you using a net? Birds? Harvest the fruit within one to two weeks of its normal harvest period as soon as bird pecks of the fruit are seen. Let the fruit finish ripening inside the house and off the tree. It is still considered tree-ripened.
Q: I have a common lawn with my neighbor, and it has an infestation of nutgrass that is now spreading into my lawn. How do I stop it? I’ve read sugar is a good alternative to herbicides, but I would like your help to get this under control.
A: I have never heard about sugar used to control weeds. That is a new one on me.
Nutgrass, sometimes called nutsedge, is a tough weed to control. Because it’s a sedge, the leaves look very similar to lawn grasses such as fescue. Many people don’t know it’s in a lawn because it looks similar to the grass.
It does grow faster than lawn grass, and that can be a giveaway. It’s also more upright in its growth, so that can also give it away. And, of course, when it sets flowers and seed, that can give it away.
Nutgrass is called that because of the nut or tuber that grows below ground. It’s usually brought into home landscapes as a weed when buying nursery plants. Most people think it’s a grass and pull it, but the nut in the soil is left behind. The plant and its soil are planted. From there it spreads.
When it’s pulled like a weed from the soil, the leaves separate from the underground nut easily. The underground nut regrows new leaves. If the leaves are pulled over and over, as soon as you see them, the nut eventually gives up, exhausted, and dies. That is a common organic strategy for controlling nutgrass without chemicals.
It’s also a common strategy when using chemicals. Weed killers burn the top of the plant down, over and over, until the nut just gives up.
A weed killer that can be sprayed on the grass and only damages the nutgrass is available. It is called Sledgehammer. It’s only available for purchase online. In prior years, it was only used by professionals. That formulation was called Manage.
A similar strategy is used when spraying Sledgehammer. But Sledgehammer actually kills a fair number of the nuts as well. But not all of them. So it must be sprayed again when the leaves appear.
When to make the second and third applications is very critical. The spray must be applied when the nut has invested its energy into the growth of new leaves. Wait too long and the leaves will rebuild the nut. As soon as they appear — no more than four leaves — Sledgehammer is sprayed again. Eventually, after repeat sprays at the right time, you have won the battle.
Bob Morris is a horticulture expert and professor emeritus of the University of Nevada, Las Vegas. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.