The Pistachio Nut Tree is native to Iran and is grown in several parts of the world that have similar climatic conditions - including California and parts of Australia. They are a deciduous tree that requires hot summers and cold winters including frosts, such as exists in a large part of the WA wheatbelt and goldfields area.
There are male and female trees with the male being a pollinator only, which is transferred by the wind and the female tree growing the fruit. It is possible to have several female trees to one male tree; the ratio depends on the size of the orchard.
The pistachio fruit is similar in appearance to a bunch of grapes. It has a split outer shell, exposing the kernel (hence the name - the Smiling Nut).
A well-managed pistachio tree provides approximately 10kg of fresh nuts at 10 years of age, with more production as the tree matures.
It is necessary to irrigate pistachios for maximum fruit production, however they can tolerate partly saline water.
They are drought resistant, but may not produce well if neglected.
The female variety grown almost exclusively in Australia is "SIRORA" which was developed by the CSIRO to suit Australian conditions and provide superior taste. These can only be propagated by grafting or budding which is usually done on "TEREBINTHUS" root stock at the nursery. It is important to stake young trees for the first 3 or 4 years to achieve a strong and straight trunk and a winter prune to maintain the right shape.
The pistachio tree has a very long life span with trees in the Middle East still producing that are over 200 years old.
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