How to graft pecan trees using the 4-flap or banana graft method

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Posted by Robert Brock | Posted in Grafting, Pecan Trees | Posted on 24-10-2009

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Collect graft wood of the desired varieties in January. The best graft wood comes from trees that grew rapidly the previous season. Trees that grew poorly (including most larger trees) will not have the long thick shoots needed for grafting. If you have a particular tree you want to collect from and the growth is not sufficient to use, you can sometimes cut back a few branches to stimulate the kind of growth needed. The folks that sell graft wood often use this approach to stimulate their trees to produce lots of growth. You will need pieces ranging in from finger to thumb size. Graft wood bigger than this can be used but it may be difficult to cut with bypass pruners. Most people cut wood into 12 inch lengths so that two grafts per stick can be made. I like to cut it into 8 inch lengths because it is easier to fit it into 1 gallon plastic storage bags. Wrap the graft wood in moist (not wet) paper towels. Be sure and label the bags with the varieties. Alternatively, you can purchase graft wood. The graft wood must be kept dormant, so keep it in a refrigerator. If you purchase graft wood, try to purchase it early in the season and get it in the refrigerator as soon as possible. To four flap or banana graft you must graft dormant wood (bark is tight to the wood and is not easily removed) onto actively growing (bark is slipping and is easily removed) wood.
You will need the following items:

Graft wood
bypass hand pruner
sharp knife
rubber bands
grafting tape (available at most nursery and home improvement stores.  Often sold as green garden stretch tie),
aluminum foil
plastic sandwich bags (I like to use the kind that comes on a roll), and something to carry it all in to keep it in easy reach.
Apron – I use a nail apron for this but have also used a five gallon bucket.  The bucket can also be turned over to use as a chair for working on shorter trees.

Pick a spot on the tree you want to graft that is in the same size range as the graft wood.  Long term it is better to make your graft higher than where a tree shaker will one day attach as the seedling bark is usually rougher and thicker.
Cut the tree with the bypass pruners. Cut any limbs that will get in the way of performing the graft on to tree.  This is a good time to cut back any other growth on the tree that is higher than graft from side or other limbs.  You want the graft to be the future dominant central leader.
Wrap a rubber band around the tree and roll it down 3 inches or so.  The rubber band will be needed later in the process to temporarily hold things together.
Make four straight vertical cuts in the bark on the tree about 1 ½ to 2 inches long.  The four cuts should be at 0, 90, 180, and 270 degrees when viewed from the top.
Select a piece of graft wood about the same diameter as where the tree has been cut or maybe a little larger.  If the graft wood is smaller it may still work but the success rate will be lower.

Using bypass pruners, cut off about ½ inch from the bottom of the graft wood.  Note the buds should be pointing up. Remove the lower couple of buds by rubbing them sideways.  You should leave at least two bud packages on the upper part of the graft wood.  Removing the buds makes it easier to perform the graft and also prevents them from growing in the plastic bag that will be added later.
Using a sharp knife, make four flat cuts on the graft wood about the same length as you made on the tree earlier.  These cuts should not be very deep.

When done properly the round graft wood will end up almost square and there will a section of bark between each cut extending all the way to the end.  If you end up with no bark showing between two flat sections, either cut the graft wood shorter and try again or discard it and try again using a new piece.

Peel the four flaps of bark back on the tree like peeling a banana .

To avoid prolonged exposure of the cambium tissue, only perform this step when you are ready to immediately place the graft wood in place.
Using the bypass pruners, cut out the center section of wood.  Hold the flaps of bark out of the way to prevent damaging them with the bypass pruners.
 Note: the bypass pruners and your hands should be free of oil.

The center section is removed, and the four flaps remain.
Place the prepared graft wood between the four flaps.  Try to align them so the narrow sections of bark line up with the cuts on the tree and the flat sections line up with the flaps of bark
Roll the rubber band up to hold the four flaps of bark in place.  This should also prevent the graft wood from falling out of the tree while you are working on the next steps.
Using a section of grafting tape, start wrapping the graft firmly starting below the cuts on the tree to above any cuts on the graft wood and then back to the bottom again.

Overlap each wrapping slightly.  Leave a short piece sticking out as you begin wrapping and you will have something to tie on to when you complete it.  Tie off the grafting tape to itself.

Remove the rubber band being very careful not to damage any of your buds on the graft wood.
Place a piece of aluminum foil (most reflective side out) around the wrapped area.   This is to keep the graft cool and moist while the cambium tissues grow together.
Tear a hole in one of the corners of a plastic bag and place it over the graft being careful not to damage any of the buds.

Tie the bag in place using two short pieces of grafting tape above and below the wrapping but still within where the aluminum foil is covering the graft.
The initial graft is complete but we are not quite done.  There is some aftercare.

bullet If the buds start growing in less than a week the graft will most likely fail.  The vascular systems of the tree and graft wood usually need at least two weeks to join together and make a successful graft.

bullet It is a good sign if the buds start swelling in two to six weeks and then growth may begin on the graft.  You will need to prevent any other shoots from becoming dominant during the first growing season.  The other buds on the tree will usually break before those on the graft and they can easily outgrow the shoots on the graft.

bullet If after six weeks there is not any bud swell, the graft will most likely fail.  You can scratch the bark on the graft wood and see if it is still green.  As long as the bark remains green there is always hope.  If it looks like the graft is going to fail, allow the tree to grow as there is always next year to try again on another shoot.  You can also try bud grafting July through August on some of the new shoots from below the graft.

bullet Once the dominant shoot on the graft wood has grown six inches or so, you may want to brace it with something. I  usually use a  stick left over from clearing or a piece of bamboo.  You  can use grafting tape to attach the stick to the tree in a couple of places and loosely tie the growing shoot to it.   I’ve had several grafts blow out in thunderstorms and now I brace any that make much growth the first year.  I haven’t had any grafts blow out after the first growing season.

bullet At some point you can remove the bag, foil and grafting tape from the graft. I usually wait until the next winter but only because I just don’t get around to it until then.

bullet At some point you will need to remove all the growth from below the graft.  You can do this gradually over several seasons or all at once.  Don’t be surprised if you get a lot of growth if in one season you remove many side limbs below the graft .  I usually let the tree tell me how much to remove.  If the growth on the graft is slow, I will remove all growth and limbs below the graft.  If the growth on the graft is more than six feet in one season, I may only cut off the lowest limbs below the graft.