Friday, January 7, 2011

Grafting and Topworking a Fruit Tree

I went out around the yard the other morning and snapped a few shots of the winter garden situation. While there is not much in the way of gardening activity, I thought I would approach a topic that should be done in the next couple of months if you are interested in attempting it.

Today we are going to have a how to session. We will be top grafting an existing fruit tree. There are a variety of reasons why we might do such activity.

The first reason (and the one why I did it) is that the grafted scionwood (woody shoots taken from the new growth of a cultivated variety, such as Mac or Cortland) has died. The hardy rootstock (the rooted base of the tree to which the scionwood was attached/grafted – a very hardy, usually dwarf type tree, with a sturdy, disease resistant root base, and precocious fruiting habits) is still alive and has sent up its own healthy stem. Unfortunately while this rootstock has many admirable qualities as a root and trunk, its fruit is less than desirable.

In this case I cut the top off the rootstock and grafted in new material from my existing Cortland tree. More will follow on this.

The second reason to top graft is if you have a wild apple tree on your property, that bears (or forgets to) inferior fruit. Mrs. Consumer would have little appreciation for most apples that grow in the wild from seed. They are usually small, disease prone, and lacking in taste. Even breeders who know there genetics and select for specific qualities, usually end up only keeping one seedling out of thousands of attempts.

In this case, as in the first, you would cut off the top branches off the tree and rework with scionwood from your desired cultivar. What you need to be aware of with a wild apple rootstock, is that while it will grow, the newly grafted wood will possibly not bear fruit for up to fifteen years. Most wild apples are very slow to begin fruiting. Whereas, developed dwarfing, rootstock (such as M9, M26 etc) will often allow the grafted tree to bear within a year or two of grafting.

The third reason to top graft is to introduce a new variety on an existing desired cultivar. Some orchardists will simply put a scion of a known easy pollinator variety on a tree that is not self-fertile and the bees will be able to do the job, without ever leaving the tree.

Hobbiest like to try putting two or more varieties on to one tree. In a small yard you can have one tree growing five different types of apples. While this all sounds good in theory, there tends to be a marked difference in growth habits in different varieties, and usually the more aggressive variety will soon dominate the tree. At one point, I had a tree with over twenty varieties grafted on. Unfortunately this was the year that the department of highways decided that if a little salt was a good thing on icy roads, then a lot was even better. My multi-varietied tree was close to the road and did not survive; salt is especially lethal to fruit trees.

I suppose a fourth reason might be just to change the shape of the tree. Often a tree will be very lopsided in its growth habits. You could cut the offending over-sized limb off and rework it. This will allow the weaker limbs to come into their own, while your new shoots establish themselves.

I don't want to get to technical in what I'm explaining as there are any number of good books and websites with excellent drawings, descriptions and photos of the step by step process. I want you to see
that it is not difficult. Anyone can do it. It has good results. It's always fun to try something new in the garden!
Necessary tools for cleft grafting
  1. Select good strong scionwood from the tree you want to reproduce. This must be the past season's new growth. Cut the twigs off (they should be at least an 1/8 of an inch across the stem where you cut. Trim the twigs to about 6 inches long (dab the cut end with tar to keep the twig from losing vital moisture.

    Left twig, new growth is above bud, the rest is two year-old wood2nd & 3rd twigs - prepared scionwood (shaved)

     Take the twig of scionwood and shave the bark off both sides of the base. See photo above.
  2. Cut the rootstock off. This can be anywhere from six inches from the ground to above where the branches branch out. Whatever you cut off, I would make sure it (the stump) is at least ¾ of inch wide at the cut. Any less than that, and the tree is going to split wide open when you started your graft. The same applies to the top of the tree if you are just going to graft into the branches.

    rootstock tree
    rootstock cut off, ready to graft

  3.  Take a dull butcher knife and hammer it into the cut trunk or branch of the rootstock. Be careful not to split the trunk/branch too far.

    split trunk
  4. Stick a screwdriver into the middle of this split, to keep the split open. Insert two twigs into the split, one on either side of the trunk. Be certain to align the cambium layers of the rootstock and the scionwood.

    insert screwdriver in trunk split
    inserted prepared scionwood

  5. Cover all the wounds and exposed wood with a layer of grafting tar or melted beeswax.

    grafting tar covering all open wounds

    7. Be sure to place a tree guard around the base of the tree.  There is nothing more irritating than having your graft take successfully and then having a mouse girdle your tree and kill it.  I speak from experience!
treetop reworked 2 years ago, grafts are above the black spots(tar)
Second reworked tree, 2yr growth above tar

 These are trees I topworked two winters ago.  The black spots are the residue of tar.  Everything above that is the grafted scionwood.  I am hoping they have grown out enough to start to bear fruit this coming year.

And that is all I have to say today.

Musings and meanderings from the Musical Gardener.

1 comment:

  1. Too much for me. Just pack me my apples and send one-day delivery. :-) I'll be waiting!


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