Empyrean 1 cv. (Primo/Barrier 1)

Pedigree: Peach x Chinese wild peach (Prunus persica x P. davidiana)

Origin: Venice, Italy

Compatibility: Compatible with PEACH, some Japanese PLUMS and APRICOTS and with almost all ALMONDS.

Vigour: Empyrean is a peach hybrid with extraordinary vigor. The vigor of Empyrean results in quick space-filling and rapid increases in production. In young trees, high almond production has not sacrificed nut size. Empyrean shows promise of being one of the best and highest yielding almond rootstocks available for well-drained soils and, demonstrated excellent performance in various regions of the world.

Chilling requirement: Lower chilling requirement.

Nematode resistance: Resistant to Root knot nematode. Tests are ongoing for Ring nematodes. Not resistant to Lesion nematodes.

Phytophthora sensitivity: Appears similar to Nemaguard, but needs more testing.

Verticillium resistance: Slightly susceptible

High pH tolerance: Tolerant to high lime / high pH soil.

Salt tolerance: Good. Performs better than many Peach-Almond hybrids

Calcareous soil tolerance: Moderate.


Soil adaptation: Good choice for replant sites as adaptation to many soil types and soil problems. Tolerant to calcareous and alkaline soils. Tolerant to sodium, chloride, boron. Tolerant to waterlogging. Yields equivalent to top 4 almond rootstocks used in California. Rapid root system growth, well branched and deep root system assists in drought tolerance.

Rootstock Controller 6 (‘HBOK 27’)

Parents:     `OP-F2` plant from an F1 plant of Prunus persica cv.‘Harrow Blood’ (HB) × cv. ‘Okinawa’ (OK)

Resistance: Moderate resistance to root knot nematode

Grafting Compatibility: Can be used as a rootstock for dessert peach, canning peach, almond, apricot, and Japanese plum (Prunus salicina Lindl.).

Description: Produced by crossing an ‘OP-F2’ plant from an F1 plant of an intraspecific hybrid between two peach parents, that has size control ability, moderate root knot nematode resistance, less wood from dormant and summer pruning, and produces fewer root suckers.

When used as a clonally-produced rootstock with fresh market peach scions, ‘HBOK 27’ showed size reduction of compound trees.

The compound trees with ‘HBOK 27’ rootstock also had approximately 50% to 60% less wood from summer and winter pruning, and had fewer root suckers.


In addition, the compound trees with ‘HBOK 27’ rootstock that were smaller generally showed greater cropping efficiency. The ability to plant smaller trees at greater density in commercial fields provides an opportunity to recover economically viable yields per unit area.


Origin: A complex hybrid of peach, almond, plum, and apricot.

Compatibility: Compatible with all commercial almond varieties

Resistance: Tolerant to Ring nematode and Root knot nematode and less susceptible to Phytophthora species.

Soil adaptation: Viking is well adapted to well-drained loam and sandy loam soil. In addition, Viking is tolerant of alkaline soils and heavy wet soils

Vigour: Viking is very vigour, upright growth, good anchorage, deep root system. The ability to develop roots from dormant cuttings, when planted in the field. Rapid rooting and growth of the cuttings in the field, facilitates early spring budding of peaches and almonds.

Problems: The largest problem is its sensitivity to dehydration during handling at the nursery and at planting. This has occasionally resulted in new trees failing to push after planting.

Has scion compatibility with Almonds (Prunus amygdalus) and Peaches (Prunus persica)

The trees budded to Viking Rootstock are approximately 25% larger in size, have a greater number of fruit set in the second and third year of growth, the fruit being larger and more uniform in size at thinning time and at maturity having greater production of large size fruit.


  1. https://p2g.us.com/index.php/empyrean-1/
  2. http://www.anfic.com.au/portfolio-view/empyrean-1-cv-primobarrier-1/
  3. http://ucanr.edu/sites/fruitreport/Rootstocks/Search_Name/?uid=7&ds=538
  4. http://cestanislaus.ucanr.edu/files/111495.pdf
  5. http://networks.iamz.ciheam.org/grempa2015/presentations/S2-I-Rubio-2015GREMPA-IAMZ.pdf
  6. https://www.almonds.com/sites/default/files/what_to_consider_almond_rootstocks__1_0.pdf
  7. http://www.almondboard.com/PR/U.2008.08-HORT4-Duncan.Duncan.Field%20Evaluation%20of%20Almond%20Rootstocks.pdf
  8. http://shaponline.org/wp-content/uploads/2012/03/Peach-Rootstock-Trials-Jim-Schupp.pdf
  9. http://fps.ucdavis.edu/treedetails.cfm?v=3493
Almond rootstocks