Pistachios, like other nut crops, are ideally grown on deep uniform loam soils, which provide an optimal combination of permeability, water retention and root zone aeration. However, pistachio orchards can be successfully managed on soils with some limitations. In California, pistachios are typically grown on the west side of the southern and central San Joaquin Valley.
In an ideal orchard, all the space over the soil is covered with nut-bearing canopy. Because pistachios are slow to reach commercial productivity, closer spacing will hasten the onset of economic production. However, as the orchard matures, closer spacing requires expensive heavy pruning, and possibly tree thinning, to maintain maximum productivity. The needs of mechanical harvest are also a factor in orchard design: spacing must be sufficient to insert catch frames for shaken nuts, yet the canopy of a particular tree must not be so wide that the frame will not catch all the falling nuts. Close canopies maximize nut-bearing area. However, when trees canopies grow together, shaking may transmit to neighbors, with nuts falling outside the catch area. The designs below seek to balance these considerations. Given that pistachio culture is relatively new in the US (ca. 1980), current designs are based largely on observation of productive orchards. These consist, typically, of cv. Kerman on P.integerrima rootstocks, with cv. Peters as pollinizer.
- Row Width: 20 - 22 ft. (6.1 - 6.5 m)
- In-row Tree Spacing: 17 - 21 ft. (5 - 6.4 m)
- Row Length: Variable, but a break is needed every quarter mile, to accomodate equipment. At the end of each row, allow 35 ft (10.5 m) to turn the equipment.
- Loading Area: 50 ft x 500 ft. (15.2 x 152 m) to accomodate nut elevator and truck, including turning area. Placed contiguous to every 40-acre block, this area can service maximum 160 acres.
- Service Roads Road surfacing material on service roads will minimize dust .
- Two-Directional Cultivation for Complete Weed Control: not adaptable to set irrigation systems, and problems with frequent use of heavy equipment may be encountered: expense, soil compaction, dust, and erosion on rolling land; possibly viable for organic growers.
- Herbicide Use for Complete Weed Control: Application through low-volume sprinklers and flood systems (on level land), minimizes dust and equipment use; water penetration can be a problem using high-volume sprinklers. This practice results in a warmer orchard than where ground cover is used.
- Complete Ground Cover: Ground cover mowed and maintained year round; improves water penetration, though overall water use increases; facilitates use of equipment by minimizing dust, soil compaction and increasing traction over wet ground. High impact sprinklers used for maintaining vegetation may increase humidity.
- Between-Row Cultivation/Within-Row Herbicide Use: repeated discing may create a raised berm within tree row or terracing of rolling land, which may complicate equipment use.
- Between-Row Ground Cover/Within Row Herbicide Use: often used with low-volume irrigation systems which do not extend to area between rows; the ground cover may dry up , thus reducing management needs.
- Intercropping: Due to the slow early growth, and heavy early pruning, of pistachio trees, a row crop may be planted between rows of young trees. Take care that management of intercrop does not damage trees.
2012 PISTACHIO DAY PRESENTATION (PDF of PowerPoint)
Pesticides, Food Safety, GAPs, Sustainability, and the California Pistachio Industry
Bob Klein, Manager, California Pistachio Research Board
Source: Pistachio Production Manual, 5th Edition (2008)