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Grafting Procedures

To get a totally new apple variety, GROW THE SEED FROM AN APPLE, (which by nature has a combination of chromosomes contributed from the tree which had the blossom and the tree which supplied the pollen. Apple seeds will always produce apple trees, but different from either the male parent (pollen) or the female parent (blossom). The analogy is that children which share chromosomes from both parents, are as a result different from both parents. The method of obtaining new varieties is thus to grow a seed from an apple and being lucky enough to get one to create a tree better that the parents. The odds of a seed producing a better variety are very low, less than 1 in 10,000. So the strategy is to plant many seeds selecting the most promising of the seedlings. This just deals with tree vigour. Then it will take about 5 to 8 years to assess the quality of apples. Thus, the birth of a new variety is not easy. Many varieties in the past were discovered as chance seedling, resulting from no intervention by man.

The strategy of getting the proper pollen to pollinate the proper tree involves selecting the varieties which have desirable characteristics you wish to combine pulling all the petals from the blossom covering the blossom with cheese cloth to keep insects (the main pollinators) from getting another, undesirable pollen to the blossom using a small paint brush, rubbed on the blossoms of the pollinating variety to collect the pollen, and then rub the pollinated paint brush over the apple blossom under the cheese cloth. This should ensure that the proper pollen is the only pollen getting to the blossom. We know who the mother is; the trick here is to guarantee you know who the father is also.

Grafting Procedures

To create an apple tree which is an exact duplicate of a apple variety which already exists, GRAFT A SCION (piece of branch) FROM THE DESIRED VARIETY ONTO YOUR CHOICE OF ROOTSTOCK. Getting a graft to grow is usually successful about 95% of the time and it produces the proper variety 100% of the time.

Virtually all new commercial apple trees produced are grafted. Grafting, like cloning ensures that the new tree is exactly like the parent tree, since it is actually a piece of wood (scion) from the parent tree which is continuing to grow after the graft starts growing. The trick is to get enough of the cambium (growing layers, just under the bark) touching, so that they can grow together and allow fluids to pass up and down the tree across the graft. This method is the only way to guarantee that any apple tree will propagate true to the parent. So all MacIntosh trees presently grown have been vegetatively reproduced from the original MacIntosh discovered in 1729 in Dunelda, Ontario. This guarantees that all MacIntosh fruit today is the same as it was in 1729. Some minor variation (SPORTS) will occasionally occur on a tree and so a scion from this branch (sport) will become a new strain of the old variety. This is how different strains of a variety are created. The current trend is to produce redder fruit, so sports of GALA which are redder, will become desirable. This is how ROYAL GALA ( a redder variation of GALA) came into existence. It is very interesting that it is possible to patent these new sports, with total disregard for the patent on the original variety.

Apple government research centres at Summerland, BC, Canada and Geneva, NY, USA have worked to create new varieties. For instance, the Spartan was created in Summerland, BC, while the NY 429 (which just was named as Fortune) was created in Geneva, NY. One large program in the USA by Purdue, Rudgers and Indiana resulted in some good varieties all designated by the letters PRI· · · · · . at the beginning of all varieties. For instance, PRIMA, PRICILLA, PRIMATE. But with cutbacks in North American government agencies, these publicly funded research centres are being scaled back and privatized. In an article in POMONA, Fall 1995, page 8, Thirty-Three Apples from Japan, George Quesada, explains how the Japanese, however, are putting much more energy into creating new varieties since they have 10 research stations, all competing to produce another FUJI or JONAGOLD. There is a list and rating here of 33 new apple cultivars, relatively untested in North America, but a treasure chest of new varieties for the amateur fruit grower. I have tried many, but none are large enough to fruit yet.

The Process of Grafting

Grafting combines 2 parts to get a successful apple tree.
Rootstock + Scion = Apple Tree. Size of tree (determined by rootstock)

The rootstock is chosen to control the final size or vigour of the tree. A standard tree is identified as 100%. Inner Coast Nursery, Cortes Island explain that many standard trees planted in the late 1800 and early 1900 continue to grow in their nursery, because they have been able to endure droughts, deer, insects, storms and past neglect. They are a gift to the future and although they are sow to start bearing, they can easily become prolific century old trees. As a bonus, they will provide scionwood to ensure that the hierloom varieties survive for our children’s children to enjoy.

 
Name Label Size Spacing
M-25   Standard 100% 20 to 30 feet tall
M-111 Semi Standard 75% 18 feet
M-106 Semi Dwarf 65% 16 feet
M-7 Semi Dwarf 55% 15 feet
M-26 Semi Dwarf 45% 13 feet
M-9 Dwarf 25% 9 feet
M-27 Dwarf 20% 6 feet

 

All the above varieties were created in England at the Mallings or Merton-Mallings Research Centre. Thus, M-26 is called the Mallings 26. The most important other rootstock which are good include Poland (P), Antonovka (Ant), Budagovski (Bud), Borowinka, Ottawa, and Mark. Each will have characteristics which should be tested to obtain the best rootstock for your area in the desired tree size range.

Thus the type of rootstock is chosen to determine the final size of the tree.

The Apple Variety (determined by the scion)

A small piece of branch (scion) from the desired apple variety is grafted onto the rootstock, so that the scion continues to grow becoming a new tree growing upward. Scions are generally about the diameter of a pencil and about 6 inches (15 cm long). Scions must be kept dormant (damp and refrigerated) from the time they are cut until they are used.

I have chosen the M-111 (75%) or M-106 (65%) rootstock for my orchard since they are very vigourous with deep roots. These trees need no staking and are drought resistant, as our summers are very dry. In this manner, I avoid the problems associated with the small shallow root system of dwarf trees (under 40%), which need staking and irrigation to survive.

So grafting is a very exciting process to most fruit explorers,

Types of Grafting:

T-bud grafting (August)

Most fruit trees are grafted using a T-bud graft. In this case, a mature bud at the base of a leaf stem, from the desired species is inserted below the bark in a T shaped cut on the bark of the rootstock about 6 inches (15 cm) above the ground. The bark must be loose enough to be lifted so the bud can be inserted. Then the entire stem is wrapped many times with a grafting tape to seal the bud in place, keeping the bud moist and tight against the rootstock cambium (growing) layer. This (dormant) bud will not grow until the following spring, when tree is cut off above the bud, and the new bud starts to grow. It is easy to spot a T bud due to the offset shape of the new growth. The tree has a bend in it where the tree was cut off and the bud grows out the side and then upwards. As the tree gets older, this feature becomes less visible.

The wrapping performs three functions:

  • It keeps the graft air tight and thus seals in the moisture.
  • It keeps the growing cells in the bud tight against the growing cells in the rootstock.
  • It gives the graft some rigidty and strength
  • The grafting tape is removed the following spring as the bud begins to grow and swell up. The diagram shows the T-bud grafting process, below left and the growth resulting from a T-bud graft are shown below right.

A photograph of a successful T-bud graft (Aug. of 1st year) is shown above.

All tree ages are counted from the time of the graft. Thus a 2 year old tree has grown 2 years since it was grafted.

Whip and Tongue grafting (February to May- before growth starts)

In the dormancy period, before any growth starts in the spring, scions can be cut from trees and rootstocks can be readied to graft. One advantage of whip and tongue grafting is that all parts are dormant, whereas T bud grafting in August, both scion and rootstock are growing and much more vulnerable to harm.

Rootstock and scionwood must both be the same diameter. Some grafters use a vernier caliper to pick the best matching diameter on rootstock and scion.

Both rootstock and scion are cut on the same angle and are placed together so the growing layers are in perfect contact. A notch is placed in the centre of both pieces so that they lock together. The graft is then wrapped tightly with grafting tape. The tape does give some strength to the graft, but all new grafts should be staked, so that the there is no force put on the graft by wind, snow, or birds.

A diagram of whip and tongue graft is shown above and a successful photo of a whip and tongue graft (Aug. of 1st year) is shown at right. In the first year it is possible to view the graft scar (almost like a large letter "Z") as shown below, but the signs of a whip and tongue graft will become invisible after that.

Other Grafting Methods

Omega Cutter

This method has a cutting instrument which make a female omega cut in the scion and a male omega cut in the rootstock. Scion diameters must be matched. Omega cut scion and rootstock are both fitted together and wrapped. This graft usually has good strength and results.