Olive’s bulges source of roots, shoots

A: Those ugly bulges occur naturally on olive trees. Frequently you will see shoots growing from these bulges or swellings. These bulges are called ovuli and they are clusters of woody tissue. Most of this tissue, called undifferentiated or callous tissue, has not made up its mind whether it will become shoots or roots and so it is somewhere in between.

If soil is piled over these bulges, roots will grow from them. Otherwise they will grow shoots. In fact, using ovuli is a very ancient method of propagating olives and may still be done in some parts of the world.

In my opinion these ovuli give olive trees a particular character that is quite unique in a landscape setting. Please don’t worry, these swellings are normal.

By the way, when you see shoots arising from the ovuli in the early spring it is a good time to remove them. Remove them by pulling them down and away from the ovuli, popping them from the tree. This will be much more effective than cutting them. Cutting usually results in more shoots growing from those locations while popping them out usually reduces new growth.

Q: I now apply three feedings to my shrubs, one month apart, of iron chelate, sulfur, phosphate and then Miracle-Gro plant food. Am I adding too much fertilizer?

A: If you are going to apply multiple feedings to your shrubs, then make sure you apply small amounts of fertilizer at each application. Feeding your shrubs small applications is much wiser than trying to put all the fertilizer on at once. As long as you are putting on small amounts at each application, you are not applying too much.

You can apply these fertilizers to the foliage as a liquid spray or you can apply them to the soil around the shrubs. Make sure the fertilizer comes in contact with water so it can be washed into the roots.

If you are using slow-release fertilizers, you may only need to apply these fertilizers once in the spring. You can “touch up” the shrubs with a liquid or foliar application if you see that they need it. Flowering shrubs should receive a fertilizer application when they’re done blooming.

Q: We are planning to buy four trees: willow acacia, Australian bottle, tipu and Chilean mesquite. What do you think?

A: I normally try to stay away from making plant recommendations for home landscapes. There is just too much personal preference involved. Although I would like to provide some guidance.

I would not recommend the tipu for a home landscape. It is too big. It belongs in a park setting. In most parts of the Las Vegas Valley it may freeze.

All of the trees you are focusing on are fairly large. In terms of water conservation, it is best to focus on smaller trees. The only places you see large trees in a desert is near where there is plenty of water, such as springs. Remember that larger trees use more water than smaller trees.

One-story homes really do not need trees larger than about 20 feet tall at maturity. Having four trees that size at maturity may mean using as much water as about 2,000 square feet of lawn, possibly more.

Q: A friend who lives in San Diego gave me two papaya plants. I would like to know how to take care of them, given the disparate climate between the two states.

A: Papayas will handle the heat here but not the cold. Papayas will freeze at 32 F, losing the leaves and buds first. At temperatures lower than that you will lose the main stem. Unless you have a microclimate or can provide a nonfreezing microclimate for it you will have problems. Keep it out of strong winds as well.

The other problem it seems to have is sensitivity to overwatering. It requires lots of water but it must have good drainage as well. It might be best to try the plant in a container and move it into the garage during the coldest nights. It grows quite rapidly and continuously needs a lot of fertilizer as it grows.

You might try growing it indoors but it probably will not do well unless it gets plenty of sunlight for most of the day. Watch out for spider mites if it is grown indoors. If you are an inexperienced desert gardener, then papaya is not something you would want to begin growing here.

Q: When we bought our new home two years ago, it came with desert landscaping and included four trees. They were but twigs when planted and they were staked. As you can see from the photo (which can be seen by those who get my newsletter), they have grown nicely in two years. I’m looking forward to some day when I can remove the stakes.

How long do you recommend they stay in place? Our house is on the side of Black Mountain, and we do get pretty good perpetual winds here.

A: Usually we want to remove the stakes from trees after the first growing season. The purpose of staking is to immobilize the root system so the roots can take hold in the soil and keep the tree upright. The reason for staking has become distorted and now many people believe that the purpose is to support the trunk.

The reason for this is mass commercialization in the nursery trade. Tree growers now concentrate on mass production and profit margins. With a few exceptions, true nurserymen who are horticulturists and artisans have disappeared. Commercial nursery production has gone down the same road as our food production. This has resulted in trees grown too close together in larger nurseries.

Some tree varieties come out of these nurseries with such weak trunks that they frequently cannot support their own canopies. A good example of this is African sumac.

Your tree appears to be one of the Southern live oaks or a holly oak. They are usually slower growers and develop strong trunks even under the worst conditions. Certainly after two years they should no longer need tree stakes. But to be on the safe side, start lowering the supports coming from the stakes to allow more movement of the canopy and parts of the trunk. This will help build a stronger trunk through an improvement in its taper. Then, in another year, remove them.

The correct way of staking the tree is to support the trunk with stakes as low on it as possible while still keeping the tree erect. You are trying to allow the upper part of the trunk to sway in the wind without moving the roots or breaking the trunk. Back and forth movement of the trunk helps develop trunk taper and thus trunk strength.

Bob Morris is an associate professor with the University of Nevada Cooperative Extension. Direct gardening questions to the master gardener hot line at 257-5555 or contact Morris by e-mail at morrisr@unce.unr.edu.