This article is about the culinary nut and the tree that bears it. Archaeology shows that pistachio soil colour chart pdf were a common food as early as 6750 BC. California, of the United States, where it was introduced in 1854 as a garden tree.
China to California in 1904 and 1905, but it was not promoted as a commercial crop until 1929. They need a sunny position and well-drained soil. Pistachio trees do poorly in conditions of high humidity and are susceptible to root rot in winter if they get too much water and the soil is not sufficiently free-draining. Long, hot summers are required for proper ripening of the fruit. The fruit has a hard, cream-colored exterior shell. The seed has a mauve-colored skin and light green flesh, with a distinctive flavor.
The splitting open is a trait that has been selected by humans. The shell of the pistachio is naturally a beige color, but it is sometimes dyed red or green in commercial pistachios. Originally, dye was applied by importers to hide stains on the shells caused when the seeds were picked by hand. Most pistachios are now picked by machine and the shells remain unstained, making dyeing unnecessary except to meet ingrained consumer expectations. Peak production is reached around 20 years. Trees are usually pruned to size to make the harvest easier. One male tree produces enough pollen for eight to 12 drupe-bearing females.
Harvesting in the United States and in Greece is often accomplished using equipment to shake the drupes off the tree. After hulling and drying, pistachios are sorted according to open-mouth and closed-mouth shells, then roasted or processed by special machines to produce pistachio kernels. Pistachio trees are vulnerable to numerous diseases. In 2004, the rapidly growing pistachio industry in California was threatened by panicle and shoot blight first discovered in 1984. Iran around 2008 to 2015 caused significant declines in production.