Oleander bushes can be trimmed into small trees

Q: I have two 7-foot-tall oleander bushes about 8 feet apart. Can I turn them into trees by cutting all the branches to the ground except for the largest, fattest branch in the middle? I know the suckers will be a problem for a while. Also, is it safe to grow a small vegetable or herb garden between them? Is the oleander flower and leaf mulch safe around the edible garden?

A: Yes, you have the right idea. Oleanders can make very nice small trees, but the suckers at the base will be a problem for a few years.

They can be made into a single trunk tree or a multitrunked tree. Multitrunk trees are easier to manage. Select five to seven stems, or branches as you call them, coming from the base and going in different directions. Odd numbers of branches are more pleasing to the eye than an even number. Those are the stems you will keep. They should be large and vigorous.

Remove all other stems as close to the ground as possible. A reciprocating saw with a pruning blade is an easy way to remove them. Remove side branches from the stems up to a height that looks good to you. Usually this is anywhere from 2 feet up to about 4 feet.

New stems will sucker from the base throughout the growing season for several years. This is because an oleander wants to be a shrub. You are forcing it to be a tree so it will try to revert to a shrub.

As soon as suckers emerge from the base, remove them by pulling rather than cutting. If you pull them when they are very new they are easy to remove. Removal by pulling causes fewer suckers in the future than cutting them.

Oleanders are poisonous, but research from California demonstrated that leaves and stems can be composted and returned to the soil without problems for other plants including vegetables.

Q: I have a peach tree planted in 1998 with bark lifting from the trunk easily in some areas. My gardener doesn’t know what this is or how to treat it. Can this tree be saved?

A: This is borer damage and is the usual reason for peach tree death at an early age. The damage is done by the feeding of an immature form of a beetle just beneath the bark. Some people call them “worms,” but they are properly called larvae.

The adult female beetle flies looking for a mate during the spring and summer months. Once she mates she then lays eggs on many different kinds of trees, including fruit and many landscape trees and shrubs.

It appears she is attracted to trees damaged by a lack of water or intense sunlight on the limbs. Reducing damage to the tree because of intense sunlight is thought to reduce this damage by boring insects. Damage is reduced by “whitewashing” limbs, particularly on the upper surfaces, with a mixture of white latex paint and water in a 50/50 mix.

Whitewashing limbs reduces, but does not eliminate, damage created by intense sunlight. This, in turn, reduces attacks by borers. Most of the damage is either on the upper surfaces or sides of limbs that face south or west. The most intense sunlight comes from these directions.

When pruning peach trees in particular do not create large holes in the canopy. This type of pruning removes too much of the canopy and allows damage from intense sunlight.

Trees attacked by borers sometimes go into a death spiral; borers attack limbs because of sun damage, limbs die, and this opens the canopy more which allows for more sun damage and more damage by borers.

There is an insecticide that has a label allowing it to be applied to fruit trees to control borers. However, this is a systemic insecticide which makes you wonder how much of this chemical remains in the fruit after this insecticide is applied.

The best approach I have found in reducing damage to trees is removal of all the damaged and dead wood with a very sharp knife, maintain the tree and good health and let the tree heal on its own.

Q: I have a 6-year-old, multitrunked mesquite tree with bark that is beginning to peel from the trunk. It started last fall and is getting worse. Otherwise it is a beautiful tree and appears to be healthy but I am concerned I may be losing it. Any suggestions?

A: There are several different kinds of mesquite trees and it is normal among some of these for the bark to peel from the trunk as they get older. In some mesquite trees it is quite distinctive. It would be helpful if you knew which particular mesquite you have so we could determine if this is true of your tree.

However, peeling bark can also indicate a dead area developing underneath this area. You will not hurt any tree by peeling this bark back and looking more closely at the trunk. Inspect the trunk under the bark for possible damage and sap oozing from that location.

It is possible if the tree is watered too often that damage can occur to the trunk or limbs. Frequently damage from overwatering can also cause sap to ooze from the trunk or limbs. This damaged area of the trunk can lead to bark peeling.

If you peel off the bark and you don’t see damage underneath it, then assume it is natural for this tree at this age to have peeling bark and don’t be concerned about it.

Q: From my Googling, it sounds like if I want cherries in this climate a good strain is Royal Lee with Minnie Royal as a pollinator tree. Do you know if they will grow and fruit well here?

A: Cherries produce erratically in the Las Vegas Valley. In some locations cherries produce abundantly and in other locations they produce almost nothing.

For instance, at the University Orchard in North Las Vegas, we produced about 15 cherries in 15 years from 17 different varieties of trees. Virtually nothing. They flowered every year abundantly, there were no freezing temperatures after flowering that would eliminate fruit but the fruit failed to mature. In other words, the fruit failed to set.

However, some people in backyard locations here have produced cherries abundantly every year. Reports to me by homeowners are anecdotal, but varieties that produced here include Bing, Lambert and a few others known to have a high chilling requirement.

In the Las Vegas Valley we don’t have enough cold winter weather to satisfy fruit trees with a high chilling requirement. Picking fruit trees with the proper chilling requirement for a certain climate is thought to be a cornerstone of good fruit production.

A chilling requirement is the amount of cold temperatures fruit trees should sustain during the winter in order to flower and produce a normal crop of fruit. Most research supports the concept that all fruit trees must satisfy their chilling requirement in order to produce fruit abundantly.

My observations at the University Orchard don’t agree with this universal concept 100 percent. When I interview homeowners about their abundant cherry crop and the location of their trees, one common theme seems to appear: Cherry trees that produce fruit abundantly are located in areas where there is higher humidity, such as near a lawn area or a swimming pool. Higher humidity may also play an important role for a good crop of Hachiya persimmons.

In my opinion, the location of the cherry tree is more important than selecting a variety. My recommendation would be to locate cherry trees near a lawn area or swimming pool to improve your chances of having a good crop. Otherwise, it’s a crap shoot regarding cherries regardless of the variety.

Bob Morris is a horticulture expert living in Las Vegas and professor emeritus for the University of Nevada. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.