Soil, fertilizer likely to blame for kumquats’ problems

Q: I have two kumquat trees that I am trying to grow in my yard. As you can see from my pictures they are not working. I feed and water them. What is the problem? Can you help? Should I discard them?

A: Your trees are in bad shape and still quite small, less than 2 feet tall. One has yellow leaves and the other has lost all of its leaves. They are growing in rock mulch and what looks like mostly a desert landscape.

Kumquat is one of the most cold hardy of the citrus family. If you saw these problems develop in late December or January, it is possible that some of the problems may be related to cold-weather damage. Many so-called evergreen plants such as citrus will drop their leaves if it gets too cold.

The leaves also will begin to yellow or develop a “bronze” discoloration when it gets subzero.

The yellowing also might be related to a fertilizer problem. Yellowing leaves might be caused by poor quality soil amendments mixed with the earth when you planted the trees. But I am pretty confident these problems have to do with the soil, a fertilizer issue or improper irrigation.

It does not help that they are surrounded by rock mulch, and the trees should be planted at the same depth they were in the container.

I know this can be confusing so let’s handle each issue separately.

n Irrigation. Irrigations should be generous but not frequent. A tree that small can get by with 10 gallons of water at each application. If the trees are on drip emitters, you should have enough emitters or run them long enough to deliver 10 gallons each time you water.

This time of the year, watering once a week is often enough. When you start to see new growth, increase it to twice a week with the same volume of water each time. As the trees get larger, they will need more water (gallons) but not more frequent irrigations.

n Fertilizer. Go down to a nursery and buy a 1 pound container of iron chelate fertilizer. It should be iron EDDHA. For each tree, mix about 2 or 3 tablespoons in a 1 gallon container, stir it and distribute it around the base of the tree where the drip emitters are. Water it in with another gallon since it is sensitive to light.

If you can’t find a fruit tree fertilizer, get some rose fertilizer and apply it near the emitters watering the kumquat. Miracle-Gro or Rapid Gro are fine. Or get some fruit tree fertilizer stakes and drive two stakes close to the emitters.

Fertilizers are salts. Keep all fertilizers at least 12 inches from the trunk when applying.

n Mulch. If this were me, I would pull the rock mulch back a couple of feet and put down some good compost (don’t buy cheap stuff). Lightly dig it around the trees, from the trunk to a distance of about 2 feet away from the trunk. I would cover this area around the tree with wood mulch, but not bark mulch.

Keep wood mulch 6 inches away from the trunk so that it does not cause the trunk to rot if it gets wet. For older trees, it doesn’t matter.

Let’s see if this works for you.

Q: I have a narrow area and the local nurseries have privets that I was thinking of using as an espalier there. However, I have read on various blogs that birds eat the berries and they get dropped in other areas of the yard/gardens and begin sprouting up all over. They say it is considered an invasive species in many areas. Have you found this to be true here and, if so, is there anything that can be done so that the plant will not produce berries?

I was also looking for information about how often I would need to prune it as an espalier plant. I want to keep it to approximately a 6-by-10 space. This will be in a spot where it will not be easy to maintain. If you have an educated guess as to whether this would require pruning once a year or 10 times a year, I would appreciate it.

A: I have not found privets to be invasive in our desert location. You might see some popping up near drip emitters but they cannot survive in the dry areas of desert landscapes. Many plants that are invasive in Florida, for instance, tend not to be as much of a problem in desert landscapes where water is tightly regulated.

If these plants are placed where there is a constant supply of water, such as along the Las Vegas Wash, then it could be a problem. But water applied by drip irrigation in a desert climate can limit invasive species and make them much less of a problem. You still have to be careful with invasive species, but in the middle of the desert with no such waterways it is not usually a problem.

Privets are not terribly fast growers. Espalier training of trees or shrubs keeps these plants trained tightly to fences or trellises in an unnatural form. Whenever we prune or train a plant to an unnatural form it will cause more work to keep it looking good.

I think you could have a pretty nice espalier going in about three to four years with careful attention to watering, fertilizing and pruning. During the establishment period of training the plant growth to the trellis, the plant will require a fertilizer application three or four times a year to push new growth.

After being established on the trellis, most of the pruning would probably be done with a hedge shears. To keep it looking good after it is established on the trellis, pruning should be done monthly starting in March and running through November.

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