Pistachios are a wonderful nut and while you may think they are hard to grow, they really are not. The key is to live in the proper area, which is USDA Plant Hardiness Zones 8 through 10. These areas provide the vast temperature ranges that make pistachios thrive. What do I mean by this? Well, they like days to be 100 degrees Fahrenheit and above during the growing season. To aid in their dormancy, the temperature needs to be 45 degrees Fahrenheit or lower.
Beyond the temperature requirement, you will also need a lot of pistachio trees. Why? Well, pistachios require a male and a female tree. A good ratio to use is ten female trees to one male. Once you have the ratio, you can simply let Mother Nature take over. Pollination occurs in April but if you have severe April showers, expect few nuts due to the weather.
Once you have your trees purchased, you can begin the planting process. If the trees are younger than five years old, they can be kept in their pots for awhile. On the other hand, if your trees are older than five years old, you will need to get them in the ground as soon as possible.
But do not jump into digging holes in the garden space just to get the trees in the ground. Pistachios love as much sun as possible in a soil that is well-drained but one that retains moisture. Also, this tree likes a lot of space and when I say a lot of space I mean 12 to 17 feet all the way around the tree. Do not skimp on the space if you want a lot of nuts. One of the responses this tree has when it is crowded is reduced nut production.
Once you have selected the best location for your 11 trees, the next step is to dig the hole. Each hole needs to be twice the width of the container the tree is in and the same depth. After each hole is dug, do a dry run of the hole before removing the tree from its container.
If the hole is fine, the next step is to cut away the pot from the root ball and tease the roots, which consists of loosening up the soil and roots so that they are not in a ring. Next, place the tree in the hole and backfill with soil. After the hole has been filled in, add water and allow to sit. Come back after the water has peculated down through the soil and fill in as needed.
Continue to monitor soil moisture and water the tree when the soil dries out.
While you hope at this point that this is it as far as growing pistachios but it is not. Pruning is an important task that needs to be done to keep the tree healthy. It is better to start this process when the tree is young.
The first step of this process should begin in April and consists of picking three to five branches that will form the basic framework of the tree. You want the lowest branch to be 24 to 32 inches above the soil level. Anything below that should be pruned away. Next, select three to four branches that are evenly spaced around the trunk. Avoid branches that may be directly across from each other. To aid in this selection, tie ribbons around the branches that you want to keep.
After you have done that, remove any branches that shade the trunk.
In June, you will need to prune again. This pruning process is designed to reduce the size of the original branches or the framework. How much do you remove? Well, it depends on the length of each framework branch but what you want is a branch that is two to three inches in length. Doing this keeps the center of the tree open.
As the tree grows in height, you will need to select other branches that will form a secondary framework.
To keep your pistachio tree looking its best, prune three times a year. Why so often? Pistachio trees have a lot of growth outward from each branch or through the terminal bud. To encourage growth and lateral branches, pruning and/or heading back will need to happen often.
While your tree will get nutrition through photosynthesis, it can use a dose of fertilizer. Pistachios really do not require anything special and actually thrive on a balanced fertilizer formulation such as a 10-10-10.
Pistachio trees have very few problems, which include verticillium wilt, cotton root rot, and crown rot. Verticillium wilt is caused by a soil-borne fungus disease that is transported through water movement. When a slight case of wilt appears, the plant material above the wilt will die back but the tree will survive. On the other hand, if the wilt is severe, the tree will die in one to two days.
How do you prevent this verticillium wilt? Start off by planting only pistachio varieties that are verticillium wilt resistant. Next, do not plant the trees in areas where cotton was grown. Lastly, help the sun sterilize the soil. While this sounds like a big deal, it is really not and can be done by you. To begin this process starts right after a rain. Once the sun has come out, stretch black plastic over the whole area and secure to the ground. Allow the plastic to remain on the soil for four weeks.
If you already have trees in the ground and have seen symptoms of light wilt, go ahead and use this technique. It has been found not to have a negative effect on tree roots.
Cotton root rot is another disease that causes wilt but also a discoloration of the leaves. Pistachio trees with this disease will first have leaves that turn a light yellow and then bronze. After this happens, the leaves will wilt, which is followed with branch death. If the symptoms of this disease present themselves, begin a program by which you side dress the tress with a green manure. This helps stimulate beneficial bacteria and fungi. This in turn will strengthen the immune system of the soil and in doing so will fight off the cotton root rot.
Crown rot is the last common plant disease that attacks pistachio trees. This disease sits up house in soils that drain poorly. While pistachio trees that suffer this ailment can survive, their growth will be permanently stunted.
There are very few insects that attack the pistachio tree but those that do can cause some major damage. Stinkbugs and leaf-footed plant bug are just a few but these two bugs really do not cause that much damage. On the other hand, the navel orange worm is one that can cause a lot of damage. This damage starts when females lay their eggs in the cracks of the nut. Once the eggs hatch, the kernel or nut is consumed by the larvae.
If you find this pest on your pistachio tree, you have two forms of treatment. One is to remove the fruit from the tree as soon as possible to reduce the damage. The second choice is to spray the tree with an insecticide late in the growing season.
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