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Tuesday, November 15, 2011

Watering a Lawn May Not Be Enough For Trees Growing in a Lawn

Q. My tree is 30'x 25' and it is in a lawn area. We follow the SNWA guidelines for watering our lawn. Very little die back has occurred on this tree, and the only fertilizer it gets is what it steals from the lawn.
Tree dieback after the lawn was removed and rock
landscaping replaced the lawn.

A. Watering enough for a lawn is not enough for a tree planted in the lawn if you are not overwatering the lawn. Watering a lawn is enough for the lawn only if you are watering it correctly.

            When you put a large tree on it then you must deep water the tree as well as water the lawn. Different types of trees require more or less water than others. Tree water use is dictated by the size of the tree and the type of tree. Size is most critical. The only time trees do well in lawns is when the lawn is overwatered. The reason trees did well in lawns in the previous years is because lawns were overwatered.

New growth is often a different color from
the older growth
            As the price of water has gone up, people have chosen to conserve more and follow lawn watering guides more closely. This has caused some trees to be underwatered even though they are in lawns.

            Lawns are big fertilizer hogs, particularly nitrogen. If you apply fertilizer to the lawn then the lawn is what is going to get the fertilizer due to its extensive fibrous root system. Trees should be fertilized separately from the lawn with applications in the rootzone, just below the rootzone of the lawn so that the lawn does not burn.

            You can judge if the tree is growing enough by looking at its new growth this past year. It will be a different color than the older wood. Or you can see where the previous year's growth stopped. On a tree that size you should get 12 or more inches of new growth each year. If not, then something is wrong. It might be a lack of water or lack of fertilizer or both.

Modesto ash decline
            I don’t know the type of tree you have but make sure you do not have Modesto ash decline if the tree is Modesto ash. I sent to you a picture of Modesto ash decline and have posted it on my blog. It is common here but does not hit every Modesto ash. I have been working with this problem for over 25 years with other professionals and no one has been able to determine its cause. This is why I no longer recommend this particular ash tree.

Several Options Available When Fertilizing Plants in Rock Mulch

Q. I know that this is not the time of year to fertilize plants, but I have a few questions regarding that subject now that it is on my mind. Do you have any suggestions for good way to apply fertilizer to plants that are in rock mulch? It's somewhat of a hassle to move the rock from around the plants, apply granular fertilizer, work it into the soil, and then replace the rock. I've used Miracle-Gro for foliar feeding, but they recommend that you feed the plants every 7 - 14 days. Is there another liquid option that only needs to be applied once or twice a season?

A. Let's cover a few options that you can use to fertilize plants in rock mulch.

            The liquid drench method. You can take a fertilizer which is soluble in water and dissolve it in a bucket of water and apply it to the root area where it is irrigated. This works very well with iron products that should be applied to the soil provided the product dissolves or is suspended in water.

            The dry fertilizer drench. Apply a dry fertilizer to the rock mulch between the plant and its source of water. Take a hose with a nozzle and wash it into the mulch. Make sure the fertilizer is not applied too close to the plant or the fertilizer might damage or even kill a plant.

One type of fertilizer stake with a plastic cap for driving
the stake into the wet ground with a hammer.
            The fertilizer stake method. Take a fertilizer stakes and either push them or hammer them into the soil after an irrigation and in the area close to the source of water. Of course you will use the plastic cap that comes with the stakes when you hammer them into the soil.

            Foliar applications of fertilizer. This works quite well but as you mentioned it is short-lived compared to a soil application. Make sure you use a wetting agent with the foliar spray.

            Install a fertilizer injector. These can be very pricey. Remember that with an injector the fertilizer is applied in proportion to the amount of water that is given to a plant. Those plants which receive more water, receive more fertilizer. It is important to have an irrigation system which applies to water correctly if this is to work well.

Increasing the Size of Pomegranate Fruits

Q. We have a pomegranate tree which grows fruit but not to the size of those that sell in stores or larger, they are very small.  This tree is growing on a slight hill and gets watered for about 20 to 30 minutes a day, plus my wife gives it an additional 2 gallons of water almost every day during the summer months.  What can I do to get larger fruit and more of it?

A. Increasing the size of your pomegranatefruits is more about pruning, watering and fertilizing than anything else.  Larger fruit will be produced on older wood so pruning a pomegranate to be more like a tree than a shrub will help. 

            During fruit formation it is very important to make sure pomegranate receives adequate water.  Water shortages during fruit development will result in smaller fruit at maturity or split fruit before the fruit matures.  Irrigations should not be daily but they should be applied in larger quantities but less often.
One fruit has already formed. The flowers arising from
the same point of attachment are removed to cause
the remaining fruit to get larger.
            Fertilize pomegranates lightly or in moderate amounts in February.  More fertilizer does not translate to more fruit or larger fruit.  But adequate amounts of fertilizer will.  Mulching with organic mulch around the tree will help.

We do some thinning of the trees when the fruits are about the size of walnuts. The only thinning done is when the fruits are arising from the same point of attachment. Then they are thinned to just one fruit. This has to be done all through the flower and fruit development period and not just thinning once but several times.

Wind A Problem for Fruit Trees But Maybe Not for the Reason You Think

Q. I am writing you in regards to a problem I'm having with my fruit trees in the spring when the winds are here.  I have a tree that grows 5 kinds of citrus fruit; Pink Lemonade, Bearss Lime, and 3 varieties of oranges (Washington Navel, Honey Mandarin, and Valencia).  I also have two other trees, a lemon and an orange, but do not know their variety.  My problem is the winds in spring when they lose their blossoms which then causes them not to bear fruit.  These trees are planted near the south wall in my backyard.  How is it best to prevent the loss of the blossoms in the spring due to wind?  How is this done in your orchard?

A. I do not believe that wind is blowing the flowers off of your trees.  In order for that to happen, you would need it gale force winds.  It is more likely that there was a dip in temperature causing a little bit of freezing damage. 

            All of these trees you mentioned cannot withstand cold temperatures.  Just the slightest freezing temperatures will nip them and cause them not to flower or drop their flowers. The most cold tolerant in the group is probably the Pink Lemonade which is most likely Eureka lemon which may withstand 26° F.  Just the slightest freezing temperatures will nip them and cause them not to flower or drop their flowers if nipped during flower formation. 

            All of these trees must be in a warm microclimate if they are to produce any fruit in the Las Vegas Valley.  And even if you have a warm microclimate, the chances of production will be iffy due to late spring freezes.

            The best advice I can give you is to provide some wind barrier to the area of the yard where they are planted. Wind combined with low temperatures can make freezing damage worse in the spring.

Full-Sized Peach Tree Not a Good Container Idea

Q. In March of this year I planted a 2 foot tree with few leaves.  It now has grown to 4 feet with a wide spread of branches. It is planted in an 18 inch pot in the southeast section of my yard.  Will this tree continue to grow in a container?  If so, should I transplant it to a larger container? I grow citrus trees in containers and in the ground successfully.  This is my first attempt to grow a peach tree.

A. I am not sure that putting a full sized peach tree in a container is a good idea. It is going to get REALLY big in there unless you can get a huge container.  A better selection would probably be one of the miniature peaches like Bonanza, Bonanza II, Eldorado, Garden Gold or Pixie. There are others but I do not know how they might perform in our climate. The fruit is okay, not great and that has been the problem with miniatures.

            I do not think a standard sized fruit tree will live as long in a container and will probably have to be replaced sooner than one in the ground. But if you do not have the room then go for it but put it in a very large container. The larger the better.