Pistachio

Pistachio, Pistacia vera, is a deciduous tree in the family Anacardiaceae grown for its edible seeds (nuts). Pistachio is a small to medium sized tree with a branching main stem (trunk) and a spreading growth habit. The leaves of the pistachio are pinnate and composed of five individual oval leaflets. Male and female inflorescences are produced on different trees (dioeceous).The flowers are small, brownish-green in color and lack petals. They are produced on panicles, each possessing several hundred flowers. The fruit of the tree is a drupe with an oblong kernel covered with a thin, bony shell. The shell splits along its long axes when mature. Pistachio trees can reach up to 20 ft (65.6 ft) in the wild but are generally smaller under cultivation. They reach maximum productivity in terms of fruit production after approximately 20 years and can live for several hundred years. Pistachio may also be referred to as green almond and originated from western Asia.


Pistachio nuts are eaten as a snack food, usually after salting and roasting.


Basic requirements Pistachio trees grow best in areas with a long hot summer and cold winter as the tree has a chilling requirement. The tree is tolerant of frost and can withstand winter temperatures as low as -20°C (-4°F). Trees are also drought resistant and can be grown on a wide range of soils, including rocky or stony soils, without irrigation but trees will grow optimally in well draining, deep sandy loams. Pistachio trees are wind pollinated and require the planting of both male and female trees for successful pollination and fruit set. Propagation Pistachio is usually propagated by budding on to a suitable pistachio rootstock. Rootstock varieties vary widely between growing areas. Budding is usually carried out in the Fall with the budded tree being planted the same year or the following year depending on the size of the seedling. Young trees are planted by digging a hole large enough to accommodate the root ball. The tree should be planted about an inch lower than it was grown in the container. Tree spacing varies depending on whether irrigation is used. In irrigated orchard, trees can be spaced in a 6 × 6 m (19.7 × 19.7 ft) grid pattern. In arid regions where supplemental irrigation is not used, trees may be spaced 8 × 10 m (26.2 × 32.8 ft) apart. Both male and female trees must be planted in order for the trees to bear fruit. Ratios of males to females vary from 1:8 to 1:11 males to females. General care and maintenance Pistachios have a similar nitrogen requirement to other nut trees. Fertilizer should not be applied in the first year following planting but in the subsequent year, each tree should be supplied with 1 lb of ammonium sulfate split between two applications over the course of the growing season. In the years following, trees should be fertilized with actual nitrogen with application rates varying from 100 to 150 lb per acre. The nitrogen should be split evenly into two applications over the growing season. no nitrogen should be applied after June to prevent vigorous growth that may delay the tree entering dormancy, potentially leading to damage from early frosts. Harvesting Newly budded pistachio trees will not begin to produce fruit for five years and will not reach maximum production until the twelfth year. Nuts are ready to harvest when the hull separates easily from the shell. This period extends for 7 to 10 days. If nuts are harvested before or after this critical period kernels may be underdeveloped and shells may become stained.


CABI Crop Protection Compendium. (2008). Pistacia vera (pistachio) datasheet. Available at: http://www.cabi.org/cpc/datasheet/41033. [Accessed 30 March 15]. Paid subscription required. Herrera, E. (1997). growing pistachios in New Mexico. New Mexico State University Cooperative Extension Service. Available at: http://aces.nmsu.edu/pubs/_circulars/CR532.pdf. [Accessed 30 March 15]. Free to access. Teviotdale, B. L., Michailides, T. J. & Pscheidt, J. W. (eds) (2002). Compendium of Nut Crop Diseases in Temperate Zones. American Phytopathological Society Press. Available at: http://www.apsnet.org/apsstore/shopapspress/Pages/42848.aspx. Available for purchase from APS Press.