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PISTACIA VERA L. - Pistachio, Pistache. |
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CULTURE |
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Location: Pistachios should be planted in full sun. The size of the slow growing trees can be further controlled by pruning. When planting, avoid rough handling since the budded tops are easily broken away from the understock.
Soil: The trees do best on soils that are deep, friable and well drained but moisture retaining. It can, however, survive in poor, stony, calcareous, highly alkaline or slightly acid, or even saline soils. The root is deeply penetrating.
Irrigation: Pistachios will tolerate considerable drought but do best with deep, infrequent waterings.
Fertilization: Since pistachios grow slowly, they do not require large quantities of nitrogen fertilizer. A spring feeding of a complete fertilizer such as 10-10-10 NPK should be adequate.
Pruning: Pruning can be important to commercial growers in order to shape the trees for mechanical harvesting, but less so for the home orchardist. The trees should be trained to a modified central leader with 4 or 5 main scaffold limbs branching about 4 ft. from the ground. After initial training, little pruning is needed except to remove interfering branches. Heavy pruning reduces yield.
Propagation: The pistachio is usually propagated in California by budding or grafting selected scions onto seedling stocks of P. atlantica, P. terebinthus and P. integerrima. These rootstock species are used because of their vigor and resistance to nematodes and soil borne fungi.
Pests and diseases: A number of fungi attack the pistachio. The most serious fungal disease in California is Verticillium wilt, which can quickly kill trees of varying age. Most pistachios are now grafted to Verticillium resistant P. integerrima rootstock. The trees are also sensitive to the oak root fungus, Armillaria mellea. Insect pests include the aphid, Anapleura lentisci and several species of leaf-footed bugs and stink bugs. The nuts are also very attractive to squirrels and some birds, including bluejays and woodpeckers.
Harvest: The nuts are harvested when the husk or hull covering the shell becomes fairly loose. A single shaking will bring down the bulk of the matured nuts, which can be caught on a tarp or canvas. A fully mature tree may produce as much as 50 pounds of dry, hulled nuts. The hulls should be removed soon after to prevent staining of the shells. To enhance splitting, the hulled nuts may then be dipped into water to moisten the shell and spread out in the sun to dry. One method of salting the split nuts is to boil them in a salt solution for a few minutes, then redry and store them. Stored in plastic bags pistachios will last for at least 4 to 6 weeks in the refrigerator. Frozen they will last for months.
The pistachio is unique in the nut trade due to its semi-split shell which enables the processor to roast and salt the kernel without removing the shell, and which at the same time serves as a convenient form of packaging. About 90% of California pistachios are consumed as in-shell snacks. Shelled pistachios are utilized commercially in confectionery, ice cream, candies, sausages, bakery goods and flavoring for puddings. They can also be added to dressings, casseroles and other dishes.
Commercial Potential: Pistachio nuts are considered one of the prime edible nuts, along with almonds, macadamias and cashews. The production of pistachio nuts in California has increased dramatically in recent years, from some 4-1/2 million pounds in 1977 to over 80 million today. With additional promotion, production is estimated to ultimately exceed 129 million pounds. |
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CULTIVARS |
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Many varieties of pistachio have been developed, because the crop has been grown for several thousands of years. In California some 13 cultivars have been tested, including Kerman, Ibrahmim, Owhadi, Safeed, Shasti and Wahedi (largest nuts of any cultivar). The first nut bearing cultivars tested at Chico, Calif. were Bronte, Buenzle, Minassian, Red Aleppo, Sfax and Trabonella. Kerman is liked by importers and processors for its size, crispness and snap when eaten. A sister seedling of Kerman, Lassen, also produces good quality large-sized nuts. The standard male cultivar is Peters. The Kerman and Peters cultivars are more fully described below.
Kerman
Female. Nut above average in size. Shells split well, are easily opened by hand. Kernel size above average, of high quality, readily shaken or knocked from tree when ripe. Tree vigorous, upright-spreading. Blooms late, produces heavily but biennially. By far the leading commercial cultivar in the U.S. Originated in Chico, Calif. from seeds imported from Iran.
Peters
Male. Good producer of pollen, its blossoming coinciding with early blossoming cultivars, as well as the later blooming Kerman. Has a tendency to be a loppy, weak grower, especially when propagated on P. vera roots. Originated in Fresno, Calif. by A. B. Peters.
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