Craig Kallsen, UCCE Farm Advisor, Kern Co.
The pistachio tree, Pistacia vera L., a native to western Asia and Asia Minor, has a long juvenile periods, producing a small crop at 5 - 6 years, and achieveing full bearing at 10 - 12 years of age. The tree is dioecious, with male and female flowers borne on separate trees. Thus, both male and female trees are required to produce a crop, with pollen being wind-borne; typically male/female trees are planted in a ratio of 1 to 19 - 24; the tree is deciduous, becoming dormant in the winter, and alternate bearing, which means the crop is larger in alternate years. There were 88,000 bearing and 23,000 non-bearing acres in 2008 (CASS survey) in California. Edible nuts are borne laterally on year-old wood. The cultivars below are species Pistacia vera L.
- Kerman: Primary female cultivar; released in 1957; large yields of large light green-ish yellow kernel, minimal flavor; strong alternate bearing tendency, high blanks in some years, high level of non-split nuts, late maturity may result in exposure to third flight of navel orangeworm
- Golden Hills: Female cultivar; released 2005; in comparison to Kerman, similar yield and kernel size, fewer blanks, and higher percentage of edible, inshell split nuts, flowers approximately 1 week earlier, and matures one week earlier; evaluation ongoing.
- Lost Hills: Female cultivar; released 2005; in comparison to Kerman: similar yield and larger kernel size, fewer blanks and higher percentage of edible, inshell split nuts; flowers approximately 1 week earlier and matures 10 days earlier; evaluation ongoing.
- Peters: Primary male cultivar; abundant pollen, shed over 2+ week period (considered long), initial pollen durability considered very good; under low chill conditions sheds pollen late, resulting in irregular Kerman pollination
- Randy: male cultivar, with peak flowering aproximately 10 days earlier than Peters, Randy has similar bloom period to Golden Hills and Lost Hills, and blooms is too early to serve as primary pollinizer of Kerman. Randy has a similar length bloom period to Peters: similar length bloom period, initial pollen durability is considered better.
The pistachio nut producing species, Pistacia vera L. is grown on rootstocks of different Pistacia species or interspecific hybrids. In trials measuring economic production in the first five years, the highest yields of Kerman were produced on UCB I rootstock. Kerman on Pioneer Gold I produced ca. 85% of yields on UCB I. Future yield measurement and reporting will determine if these differences persist through the bearing life of the tree.
- Pioneer Gold I (PG I): species P. integerrima; Most widely used rootstock; tolerant of Verticillium wilt; least cold tolerant as evidenced in trials in which temperatures dropped to 4 - 120F in 1989-90; least tolerant of salinity, although tolerant of up to 5120 PPM Total Dissolved Solids (TDS) in trials; high uptake of sodium and chloride probably a factor in lower yields relative to UCB1 and Atlantica in trials; prone to zinc and copper deficiencies.
- UC Berkeley I (UCB I): hybrid of P. atlantica pollinated by P. integerrima; widely used rootstock; resistant to Verticillium wilt; tolerant of salinity; prone to zinc, copper and boron deficiencies.
- Atlantica: species P. atlantica; no longer a common choice due to susceptibility to Verticillium wilt; most tolerant of salinity; most cold tolerant, which is significant during orchard establishment.
- Terebinthus: species P. terebinthus; no longer a common choice due to susceptibility to Verticillium wilt; as cold tolerant as Atlantica.
For a listing of commercial suppliers and nurseries: Administrative Committee on Pistachios
Source: Pistachio Production Manual, 5th Edition (2008)