Q: I have a Desert Museum palo verde that was damaged during a windstorm. One of the branches blew off and damaged the trunk. It is an eyesore. Should I replace it?
A: I would let the tree heal on its own but help it along the way.
Healing takes two to three years if the tree is kept in good health. To do that, clean up the wound and apply management practices that encourage it to heal.
Don’t use any paint or “tree healer” as this was proven ineffective in past research and could actually slow the healing process. If you do paint the damaged area, use latex water-based paint.
If there are any splinters resulting from the damage, remove them with a sanitized knife. Make the damage, and healthy areas surrounding it, as smooth as possible so the healing is faster and pleasant to look at.
With that same knife remove the outer bark so that the edge is smooth and clean, and the damaged area is shaped like a vertical football. The damaged area will compartmentalize and the tree will roll over the area as it heals over the next couple of years.
When the tree starts to grow this spring, make sure it gets adequate amounts of water and fertilizer. Good health practices help the tree to heal faster.
To reattach or repair a limb split, or otherwise damaged area from a tree during a windstorm, is usually a lost cause. If done successfully the limb must be reattached, or repaired, within minutes or even seconds after it is severed or broken. Time is very important so that the damaged area doesn’t “dry out” before it is repaired.
Q: I have a tree that was staked and now the wires used in staking it are starting to strangle the tree trunk.
A: That’s a common problem on large, staked trees planted in home landscapes. It’s a gamble on the wind whether to stake or not to stake. I encourage people to stake nearly all plants. It’s cheap insurance.
On smaller 5-gallon plants (sometimes even 15-gallon shrubs) the small, square, green nursery stake found in the container may be adequate if cut loose from the plant, driven or pushed into the moist, solid ground beneath the plant. Retie the plant when you’re finished. Always have some half-inch, stretchable green nursery tape on hand. It’s very useful.
The purpose of staking any plant is to keep new roots from being damaged during establishment. The movement of roots usually happens during strong winds. Planting in wet holes and amending the backfilled desert soil may get around the use of stakes with smaller plants. Use your judgment.
Typically staking is only needed for one growing season and then removed. One growing season is all that is needed to establish plant roots in the surrounding soil and make the plant secure against the wind.
Some homeowners may think the reason for staking is to hold the tree upright. That’s only partially true.
On occasion, more than one growing season of staking may be needed when planting trees grown too close to each other in wholesale or production nurseries. In cases like these, metal ties are loosened and then retightened at the end of each growing season to prevent choking the trunk.
Remember, plants grow in two dimensions: length and girth. Sometimes excessively tall and weak plants must be pruned smaller to encourage new, stronger growth.
The proper way to stake a tree is to allow the canopy and trunk of the tree to move but not its roots. The movement of a tree’s trunk allows it to gain taper (become stronger) as it grows in size.
Trunk taper may or may not be missing because of production nursery practices. Properly grown trees have a tapered trunk as you look at them from top to bottom.
Q: I have a Meyer lemon tree in a pot on a south-facing patio. The wall near it faces east and there was a large pine tree out front, so it receives shade in the afternoon. There are quite a few yellow leaves that just appeared. All the new fruit has turned black. It seems to me that maybe I just need to replace this tree. The lime tree is doing very well in a similar location.
A: Meyer lemon typically flowers sometime in January and February. The fruit can be harvested starting about now, and this harvesting, finished by January, encourages new flower development for next year’s production.
Producing flowers and then fruit in midfall is early for Meyer lemon. Early flower development can be a sign that it is under some sort of stress. Certainly, it’s not normal for this type of tree at this time of year.
All fruit trees and vegetables need a minimum of six hours of full sunlight. Eight hours is even better.
In home landscapes, the best sunlight in the summer months is during the cooler morning hours. Partial shade may be pleasant for people sitting on the patio but not for many plants that produce fruit or vegetables.
If shade is present during most sunlight hours, then I would recommend an ornamental plant for that spot with variegated or colorful leaves, not a flowering or a fruit-producing plant. A nonflowering ornamental handles shade better than a flowering plant, whether those flowers produce fruit or not.
Growing a shallow-rooted plant or plants at the base of a deeper-rooted plant is a big no-no regarding how often water is applied. Shallow-rooted plants signal they need water applied more often than deeper-rooted plants, so they get water applied more often than the watering frequency needed for deeper-rooted plant needs.
This type of watering can suffocate the roots of a deeper-rooted plant. Watering a deeper-rooted plant too often can produce leaf drop, flower drop, fruit blackening and a tree that’s loose in the soil. Trees that develop collar rot disease need to be staked after just a few years of growth. Does that sound like your fruit tree?
I would replace this tree with a plant that requires moderate to low levels of sunlight. If you want to grow other plants along with it, select plants with a similar rooting depth and need for applied water.
Q: I had two pecan trees that are now 25 years old. One variety has round nuts and the other one has oblong nuts. This is the first year in 25 years they have produced nuts that have black spots and are bitter tasting but the outside of the nut looks normal. Any idea what the problem might be?
A: Pecan nut problems are hard to diagnose. The nuts themselves can be bitter if some of the husk is attached to the nut. But yours sounds like a disease issue to me. Perhaps it was our wet early summer and spring that created the problem.
The most common disease of pecans is scab. When it is a wet spring, after a rain, it is wise to spray the trees in March with a fungicide such as Bordeaux or copper sulfate. If it rains again, spray it again after the rain has stopped.
The problem is spraying these trees top to bottom since there are no systemic fungicides that can be applied to the soil and taken up by the roots. The lesions on the outside surface of the shell this disease produces are difficult to see and does produce an off flavor once inside the meat.
I must guess a little bit, but the varieties popular about 25 years ago in the West were oblong nut varieties called Western Schley, Mahan, Wichita, Mohawk and Cheyenne. The older and round nut varieties were either Burkett or possibly Choctaw.
The reason I mention it is because there are probably well over a hundred varieties of pecan. The more recent hybrids are smaller, produce nuts sooner, are less likely to bear nuts every other year (alternate bearing) and don’t need a pollinator tree. Also Choctaw and Cheyenne varieties were considered resistant to this disease.
Even though pecan trees can handle our summer heat and poor soils, I don’t recommend them for our area because of their size and water use. Pecan trees can get big, growing 60 to 100 feet tall and 30 to 50 feet wide, and have no semi-dwarf or dwarf varieties that I know.
Their size dictates they use a lot of water. They do have a sizeable tap root so they possibly could be used where there is shallow underground water.
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.