David Doll, UCCE Farm Advisor, Merced County and Carolyn DeBuse, UCCE Farm Advisor, Yolo and Solano counties: editors
The selection of an appropriate almond rootstock is very important to establish a successful orchard. There is no single best rootstock. A careful analysis of the traits of those available should be done with regard to the unique soil, pest, and weather conditions of the orchard site. Almond rootstocks currently available include Nemaguard, Nemared, and Lovell peach; Marianna 2624 plum; various peach and almond hybrids. Rootstocks can be either seedlings or vegetatively propagated (clonal).
- Nemaguard (Peach) (Prunus persica x Prunus davidiana): most widely planted rootstock for almonds; resistant to root nematodes; all almond cultivars are compatible; out yields almond-rooted trees; somewhat less tolerant of heavy soils and excess water; can be affected by crown gall, oat-root fungus, and crown rot.
- Lovell (Peach): preferred by growers in Sacramento Valley for its low-levels of root knot nematode and greater tolerance to heavy soils and higher rainfall amounts; susceptible to nematodes, oak root fungus, crown rot, and crown gall.
- Bitter Almond: seldom planted in California and not readily available, except in areas with no irrigation; later bearing; tolerates drought better than peach or plum rootstocks as well as soils high in lime and boron; sensitive to wet soils. Sensitive to nematodes, crown gall, oat-root fungus, and crown rot.
- Marianna (Plum): able to tolerate some heavy, wet soils and soils infested with oak-root fungus; resists root knot nematodes and crown gall; incompatible with Nonpareil cultivar
- Peach/almond Hybrids: nematode resistant; drought tolerant; high vigor; deep rooting; tolerance to calcareous soils; susceptible to crown and root rot; somewhat susceptible to root fungal infections, crown gall and root knot nematodes.
For a listing of suppliers and nurseries see: Almond Board of California
Source: Almond Production Manual (1996), UC Division of Agriculture and Natural Resources.