Lack of leaves in winter makes it ideal time to prune

Q: When is the best time for pruning trees in Las Vegas, specifically my African sumac, California pepper, carob and mulberry. When I cut, I'm wondering is there any worry of infection or should I just cut away?

A: Traditionally the best time to prune deciduous ornamental trees is during the winter. This is when deciduous trees have dropped their leaves.

At this time you can see the basic architecture of the tree . It is easy to see some hidden things such as crossing limbs, where one needs to be removed, broken limbs and limbs oriented down or growing straight up. These weaker limbs or poorly structured limbs can be removed.

Most of your effort should be total removal of a limb or branch that is offensive. This is done at the point of origin of the limb or branch, leaving no stub. All pruning equipment should be sharpened, adjusted and sanitized.

Light pruning, pruning to remove small offensive branches or new growth, can be done any time of the year. It is much easier to remove this new growth when you see it than to wait until it is older and more of a headache to remove.

Evergreen trees such as sumac also are usually done when the tree is dormant, or no longer growing, during winter . If the tree is sensitive to very cold weather, it is best to wait until most of the cold weather has passed. Then you can remove any freezing damage at the same time .

If you are going to limb up a tree by removing lower branches, aesthetically it would be best to try to leave about two-thirds canopy and one-third trunk by the time you have finished your pruning. Larger limbs may require a "1-2-3 cut" with the final cut leaving the so-called shoulder of the limb still on the trunk. I will post some pictures of these types of things on my blog soon.

Q: There are six trees on our property: a Raywood ash, which is 10 years old; Arizona ash, which also is 10 years old; California pepper (taller than our two-story house and 8 years old); Bradford pear, which also is 10 years old; a young African sumac and a young palo verde. Is now a good time of year to deep feed these trees?

A: You can deep-root feed these trees (put the fertilizer in the root and watered area at about half a foot ) now that they are preparing for winter and have stopped growing, but they should still have green leaves on the tree.

If there is no grass there, then apply it to the surface of the soil and water it in. Water the fertilizer in the root zone three times during for one week and then continue to cut back on your irrigation for these trees as you normally would for the winter.

The living green leaves on the tree will help move the water laced with fertilizer into the tree and into storage for next spring's growth. It also places fertilizer in the area of the roots for next season, provided you don't water too much. You can then skip a spring application of fertilizer.

If the leaves have turned yellow or are starting to drop, you missed it for this year. Wait until next spring. There is no advantage to applying fertilizer in the fall except possibly convenience.

Q: I have a large cactus garden in my front yard and much fruit. My cactus is the "bunny ears" type. Is the fruit of this type good to eat and does it have health benefits? I am a retired teacher and just read your article on cactus fruit. I have made jelly from them in the past. I suffer with Crohn's disease and wonder if this fruit is comparable to the Nepolia health drink that costs so much. Since Crohn's is an autoimmune illness, I wonder if this fruit has some good anti-inflammatory properties? Thank you for your time and any help you can give me

A: Sorry to hear about your health concerns. The fruit would definitely be edible but not all Opuntia-type cactuses are desirable for eating. The nopal cactus also is a "bunny ears" type but the fruit may not be as edible.

In some nopal cactus the sugar content may be as high as 30 percent, which would rival fully mature wine grapes in sugar content. I normally will get about 16 percent to 18 percent, which would rival a really good apple or peach.

A good indicator whether your cactus will be a good one is how the birds use the fruit. If birds are devouring the fruit, then it will have some really good characteristics for human consumption. If the birds leave it alone, it probably has low desirability.

As far as health benefits go, I have heard that it is, of course, high in fiber, helps lower cholesterol, helps reduce high blood pressure and is normally high in vitamin C (reds are the best) but I have not heard anything about autoimmune system benefits .

Also, if you want to start growing cactus for food, you will have to alter the irrigations of cactus to push new, succulent growth starting in about March. A deep irrigation every two weeks is all that is needed, along with a fertilizer application high in nitrogen in the spring. Compost applications at the time of planting and on the surface each year also will help push new growth.

Q: My indoor palm plant has developed a sticky-looking, shiny appearance on the leaves. Also, there are small, one-sixteenth of an inch brown spots/bumps on the leaves and stems. What is this?

A: This is probably one of the scale insects. It is living under this brown bump and sucking plant juices while totally protected by this bump or shell it builds on top of itself.

These brown bumps are what keep them alive when pesticides are sprayed on the plant. But they are susceptible to poisons or insecticides that are taken up into the juices inside the plant.

So, systemic insecticides, those that are applied to the soil or sometimes sprayed on the leaves and taken up through the leaves, can be quite effective on these protected insects .

You will have to try to find a systemic insecticide at a nursery or garden center that has a label specifically for houseplants and controlling scale insects. The shiny, sticky stuff on the leaves is the sugary excrement of these scale insects. Frequently it attracts ants.

During a three-week holiday break, I will be presenting a series of fruit tree pruning workshops Dec. 22 at the University of Nevada Cooperative Extension Master Gardener Orchard in North Las Vegas. All the major fruit and nut trees will be covered. Sessions begin at 9 a.m. For an agenda of the topics, please email me, visit my blog at Xtremehorticulture of the Desert.

Bob Morris is a horticulture expert living in Las Vegas; he is on special assignment in the Balkh Province, Afghanistan, for the University of California, Davis. Visit his blog at xtremehorticulture.blogspot.com.