Cut cactus arms can be replanted

A: From your pictures, I don’t think your cactus is a saguaro. I think it is one of the columnar cactuses, also called a climbing cactus. Well, it is a setback for the plant because the cuts make it look ugly. The plant doesn’t care, but it is not pleasing to look at.

If I’m right, and this is a climbing cactus, those cuts create new growth coming from the ribs just below the cut. The cuts will force new side growth, columns, that continue growing upward.

Another option is to remove all the damaged stems to a couple inches of the ground. Let them sucker and regrow below the cut. Remove damaged arms entirely if it looks bad. Cut these removed columns or arms into 12-inch-long segments for planting. Put them in the shade for one to two weeks to heal the cuts before planting.

After two weeks, plant them in soil amended with compost (not upside down) with about one-third of the 12 inches stuck in the ground. Stake to hold them upright until they grow roots and don’t fall over. Water every two to three weeks so that the soil is dry between irrigations.

Let the columns that weren’t cut continue to grow but lean against something upright. These cactuses will get tall if they don’t freeze back during a very cold winter.

In your picture, some columns appeared to be damaged by intense sunlight. This damage was forcing a lot of new side growth from the columns. This cactus will grow much better with amended soil and put in a location where it gets some shade from the late afternoon sun. Now might be a good time to move it to a new location and let it lean.

Q: I planted a Sophora secundiflora in my backyard about 17 years ago. Today, I noticed many of the stems are infested with an insect that looks like a type of scale to me. The stems and leaves below the infested stems look wet and sticky. The pavers underneath the plant are also wet and sticky.

A: Yes, you are correct. These brown, round bumps on the stems are scale insects. I have never seen these on Sophora, Texas mountain laurel before and I could find no reports of scale insects on this tree from anywhere.

Scale insects provide a food for ant colonies, as do aphids. It’s mostly sugar from plant sap. That’s the sticky wetness you are seeing. Ants have a vested interest in protecting and colonizing ant and scale populations because of this sugary, sticky wetness.

The most effective control of scale insects are repeat stem sprays of horticultural oils. These sprays should be applied several times during the cooler times of the growing season. Combine this spray with ant control in the same area.

Ants move scale insects around, much like they do aphids, to different plant parts and even different plants. They contribute to the spread of scale insects in trees and shrubs and can turn a minor problem into a major problem in a couple of months.

When controlling ants, use a poison bait in locations where there are problems. If there are no problems, no control treatment is necessary. Ants play a positive role in protecting plants from other insects.

An insecticide called Amdro, an ant bait, has been effective in controlling the spread of aphids by controlling ant colonies. I see no reason why this treatment would not also control the spread of scale insects. You can find Amdro ant bait at any garden center or nursery.

Most of our ants live in the ground in colonies. Identify the soil opening or openings to these ant colonies and spread 15 or 20 granules on top of an ant mound. Ants take this poisonous bait into the underground nest where it kills the entire population in 24 to 48 hours. The area where it’s applied must stay dry for 24 to 48 hours to work. Make sure the label of this product fits the needs at your site before applying it.

Horticultural oils are sprayed over the entire tree, top to bottom, if temperatures are below 90 degrees Fahrenheit and no flowers are present. Repeating this spray three or four times during the growing season provides nearly 100 percent control of scale insects.

Apply soap and water sprays to the tree seven to 10 days after the horticultural oil application. Soap and water sprays kill any young nymphs that eluded the oil application. Remember, soap and water sprays, just like oil applications, kill all insects sprayed, good or bad. Direct soap and water and oil sprays only to locations where there are problems.

Q: What is causing dying leaves on peach or apricot?

A: There is not much information to go on with this question so I will give a broad response. From the pictures sent with this message, the fruit trees appear to be newly planted, whitewashed and the central stem pruned at about waist height.

If this tree was newly planted and bareroot (no container), it must be staked firmly in place, so roots do not move during the first few months of growth. Securing the tree solidly, in one place, encourages strong, future rooting.

I assume the soil was amended with compost at the time of planting for better rooting and drainage. Build a donut or moat around the tree, 2 to 3 feet in diameter, to contain water from a hose. Water the tree with a hose once a day for three days in a row to settle the soil around the roots and remove air pockets.

When that is finished, water every other day during warm times of the year. Make sure to skip at least one day before watering so that roots can breathe. Watering every day for a month could suffocate roots and kill the tree or at least cause it to be sickly.

Bareroot tree roots dry and die quickly. These important roots provide water and nutrients from the soil and are very small, not large. These tiny roots dry out and die in seconds. Excessive drying of these roots causes transplant shock, resulting in slow growth after planting.

Bareroot trees can be finicky. You don’t see bareroot trees sold much anymore to homeowners. Only experienced gardeners should buy them. The roots of these trees must be kept moist from the time they leave the nursery until they are planted.

A common symptom of bareroot trees that have excessively dry roots is a short flush of new growth after planting followed by their death. The death of new growth looks like a lack of water. And in reality, it is. Roots have died and can no longer supply water to new growth.

If you think this might be the case, wait and see what happens after planting. In about two months, if you do not see new growth then the tree is dead and should be replaced.

Q: My dwarf Genoa lemon tree growing in a 12-inch diameter planter will be 2 years old in October. I’d like to plant it in the ground. Is this a good idea now?

A: It’s a good idea to plant it in the ground but no, not now. Late spring is the absolute worst time to move fruit trees to a new location. Hot weather is coming quickly. Wait until mid- to late-September when weather cools a bit from hot, summer temperatures.

Fall is the best time for planting and replanting, bar none. Spring is in second place, but that’s when most plants are available.

Take as much of the roots as possible in the move. Dig the new hole and have soil amendments mixed into this soil. Use this soil mixture for backfilling around the roots after it’s planted.

Plant it as soon after digging as possible. Make a moat around the tree to hold water from a hose. Water it thoroughly with a hose three times in three consecutive days. Remove the moat and turn it over to your automatic watering system.

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.