The Art and Science of Grafting
So What is Grafting? - Grafting is the ARTof connecting two pieces of living plant tissue so that they will unite, grow and develop as one plant
Grafting Terminology Scion - short piece of detached shoot containing at least one dormant bud. The upper portion of the graft producing stems and branches Rootstock (understock or stock) - lower portion of the graft. Produces the root system of the plant.
Vascular cambium - an area of actively growing tissue located between the bark (phloem) and wood (xylem). The cambium of scion must be in close contact with cambium of rootstock.
Callus - mass of parenchyma cells that develop from wounded plant tissues.
The History of Grafting - First documented by the Chinese as early as 5000 B.C. when Feng Li, a Chinese diplomat, began grafting peaches, almonds, persimmons, pears and apples as a commercial venture.
- Aristotle (384 -322 B.C.) and Theophrastus (371-287 B.C.) both wrote about grafting.
- During the Roman Empire the Romans were famous for their grafted olive trees
- In the early 1800’s grafting became common place in the United States.
- Today grafting is used by many major growers to produce hundreds of different types of agricultural and ornamental plants.
1) ToPerpetuate clones - Many plants (beech, eucalyptus, fir, oak and apple) root very poorly from cuttings. - Consequently, clones of these species are often maintained by grafting.
- Japanese maples often form poor root systems when grown from cuttings and therefore must be grafted
2) To Take Advantage of Rootstock Disease and Pest Tolerance. • Some rootstocks can tolerate unfavorable soil pressure from disease, insects and nematodes better than the scion’s root system.
- Wine grapes are grafted onto native muscadine grapes to prevent problems from nematodes and phylloxera = yellow aphid.
3) To Take Advantage of Rootstocks tolerance of poor growing conditions. - Some rootstocks are able to withstand poor quality soils (compaction, poor drainage, dry, high salt levels) better than the scion’s root system.
4) Some Rootstocks Can Speed the Growth of the Scion Into Early Maturity.
5) Some Rootstocks can increase plant growth rate and reduce nursery production time. - Some shade trees (like Acer platanoides ‘Super Form’) can grow more quickly if grafted than if grown as a rooted cutting or even a seedling!
6) Grafting Can Be Used to Obtain Special Growth Forms - With ornamentals, it is common to use an upright growing rootstock and a “weeping” or “dwarf” scion
- With fruit trees it is common to use a dwarfing rootstock to create a smaller sized plant
7) Grafting Can be used to Repair damaged trees • Trees are often damaged from winter injury, rodents, machinery, or disease. • Grafters can use a bridge graft or a technique known as inarching to repair the damage.
8) Grafting can be used to change cultivars on established plants (topworking) This method is used to: • Change unproductive cultivars or those no longer in demand • Fix poor growth habit • Change cultivars that are susceptible to insects of disease
Budding - a specialty form of grafting performed in late summer. The scion is small and typically only consists of a single bud.