GARDENING: Free seminar set for apple, pear and quince admirers

I have quite a schedule coming up for you apple, pear and quince lovers at our Lindell Learning Center, 2590 Lindell St., at no charge. On Tuesday, from 6:30 to 9 p.m., I have a seminar on apple, pear and quince management and pruning. This is open to the public. We will be discussing watering, fertilizing, insect control and pruning. The next day, Jan. 11, from 9 a.m. to noon, we will be giving a hands-on pruning workshop at the orchard, located in North Las Vegas at Ann and Horse roads.

Question: I have borers that have become a huge problem in my trees. They attacked fruit trees last year. We treated with a pesticide for borer control. It seemed to work. This year they came back in a very healthy pepper tree, killing nearly one third of the tree. The tree still seems green in the trunk of the infected part but no leaves. I treated all trees again. Should I remove the infected trunk or let it go till spring to see if it comes back?

Answer: Borers are immature forms of some type of insect. In our climate and locale they are most frequently the immature beetles or moths. Depending on which borer it might be they can attach small limbs, large limbs, the trunk, the roots, or twigs. We have some borers that are specific to one plant and others that are general feeders and can attack many different types of plants. Let's stick to borers that invade the above ground parts of trees, specifically branches, and not those that attack roots or new shoots.

This is the first I have heard of a borer in a Pepper tree. I would check and make sure it is in fact a boring insect problem.

The eggs of branch-boring insects are laid by an adult beetle or moth. They usually like limbs that are at least an inch in diameter. Unless the neighborhood has hundreds of infested trees which no one is caring for, these borers usually target unhealthy or stressed plants or plant parts.

The strategies used for controlling borers are as follows: prevention, nonchemical treatment and lastly chemical treatment. The reason I suggest chemical treatment last is because chemical treatment usually does not address the major reason for having borers in the first place. You might unknowingly be caring for the trees in a manner that encourages borers and not be aware of it.

Prevention. Borers like tree limbs with sun-damage or wood subjected to intense sunlight and under stress.

Provide trees prone to borers with a canopy of leaves that shade the limbs and trunk with filtered light. This means do not overprune a plant that is prone to borer problems. With fruit trees, this can be difficult because you want to shade the limbs but you don't want to completely shade the inside of the tree where the fruit is located.

So in the case of landscape and fruit trees you want filtered light, light that has to pass between the leaves, to penetrate the canopy. You can judge if enough light is getting through the canopy of a fruit tree to the inside of the tree by looking at the shadow the canopy casts on the ground during summer months. Ideally you would like the shadow of the tree on the ground to have speckled sunlight in it.

Trees with tender bark need to have the trunk and limbs shaded until the outside of the limbs shows signs of maturing, typically turning brown, cracking and furrowing (turns grey due to age). In the case of fruit trees I would strongly suggest painting the trunk and lower limbs up past the first the major branches we call primary scaffolds. Light colored paint helps to reflect sunlight and kept he painted portions cooler.

Make sure the branches and trunk facing south and west are painted for sure. Use light colored latex paint, not oil based types. Dilute the latex paint with an equal amount of water. When finished and done correctly, the bark needs to look like it has been painted.

Nonchemical treatment. Use a sharp knife and cut out the infested wood. This time of year it is quite likely you will find the immature borer in the periphery of the damaged area. The fiend will not be in the center of the dead area where it cannot feed. Borers feed on living parts of the tree so it will be in the area bordering the dead area and feeding on soft, succulent, wet tender wood.

Find it and destroy it. Remove all the damaged area down to fresh wood. Do not cover the area with wound dressing. Leave it alone and let it heal. If the damaged area represents more than 50 percent of the cylinder surrounding the branch, consider removing the limb at a juncture with the trunk or at a major limb below it.

Chemical treatment. Use only chemicals that clearly state on the label that it can be used for the type of tree you are treating. If it is a fruit tree, the label needs to state it is for fruit trees. If it is for landscape trees, it must clearly state so. This is for your protection. You don't want to eat fruit from a tree, or have a neighbor kid pick a fruit, from a tree that has been treated with a chemical that could possibly get into the fruit.

Follow the label directions accurately and wear protective clothing. These are poisons that can have short term and long term health consequences if used improperly.

Q: I need to plant some shrubs in my backyard and I live in the Northwest part of Las Vegas. I haven't picked any shrubs out yet, but my question is, can I plant shrubs and trees now that it is winter? And if I can, is there anything special I would need? You know how the dirt is around these parts... You can't just dig, you have to use an ax pick just to move the soil.

A: You can plant now but it is not the best time to do it. If you are careful you will be successful. The soil is cold now and there won't be much root growth until the soil warms up more. Establishing plants in a landscape means that there is sufficient root growth into the soil surrounding the root ball. I would amend the soil in the planting area with about 50 percent organic matter. Compost is best. You will not have to dig deep unless the soil doesn't drain.

It is best to dig the planting hole wide enough to allow root growth and just deep enough to accommodate the root ball. In landscapes, we mostly see plant roots growing laterally, not down, due to our shallow irrigations. Water the plants in the holes thoroughly after planting. Plant on a warm day when the soil can warm up a bit.

Cover the new planting area with about four inches of mulch to keep the soil blanketed from the cold. You can use a starter fertilizer even though there are seldom any solid results from using starter fertilizers on woody plants but it is cheap insurance. Just make sure the soil is thoroughly wet and muddy after planting and that it drains water easily in a couple of hours.

Don't use your feet to stomp the soil around the plant when you are done planting. The water should settle the soil around the roots if the water is added as the soil is backfilled around the root ball of the plant. Leave a watering donut around each plant that you can use to wet the soil every time you water for the next couple of months, even if you have planned to use drip irrigation.

If you are going to use drip irrigation, hand water the first few weeks anyway. You can replace the soil in the donut when no longer hand watering but don't pile it on the stem or trunk of the plant. The soil around the plant should be at the same level as the soil in the container or slightly higher.

You could probably water with a hose maybe once a week on new plantings covered in mulch right about now. Start drip irrigations after about four or five hand waterings.

Lastly, protect your plants from the winter cold. Come and get your free mulch from the Orchard. For directions, e-mail me or call the master gardener hot line at 257-5555.

Bob Morris is a horticulture specialist with the University of Nevada Cooperative Extension.