It’s a nice spring day, the snow has all melted, temps are nearing 50 degrees, the sun is out, the birds are singing and you decide to take a walk around the yard to see if any spring bulbs are poking through the soil. You are in a happy mood with a little “spring” in your step and then you spot it….stopping you dead in your tracks….some little vermin has girdled your prized Japanese Maple tree. The beautiful little tree you have babied for years now is in jeopardy of dying. Well, there is a chance that such damage to a tree can be repaired through a process called bridge-grafting.
First, girdling is a term used when a ring or partial ring of bark has been removed from a tree. The severity of injury or eventual death depends upon how much of the bark was removed. The phloem layer of tissue that lies just below the bark is responsible for carrying food produced in the leaves to the roots. Without this food the roots will eventually die and cease sending water and minerals to the leaves. There is some stored food in the roots which will allow the roots to function for a while but repair should be done as soon as possible.
Bridge-grafting provides a “bridge” across the damaged area so that the transport of nutrients can be partially restored. If all goes well, the leaves will manufacture enough food that will allow the tree to grow new tissue that will grow over the wound and thus restore the tree to its normal processes.
The wound will need to be prepared for the grafting process by removing any sharp edges or loose bark with a clean, sterile knife. Next you will need to remove some pencil to thumb-sized (in diameter, depending on the size of the tree) healthy branches from the same tree and one to three inches longer than the width of the wound. These graft pieces are called scions. It is important to place the flow of the graft in the right direction over the wound therefore when cutting the branch into pieces place a mark denoting the top of each piece. Trim one side of each end to flatten it so that it will lay flat against the trunk of the tree. Cut the other side of each end so that you form a wedge shape.
Next, starting from the wound edge, you will make two parallel cuts, the width of the scion, into the bark forming a flap, one at the top of the wound and one at the bottom of the wound, that the scions will fit under. When lifting the flap of bark, do it gently so that it will not break off. Fasten the scion in place with a brad if needed. Place scions about 1 ½ inches apart. It is recommended to cover the grafted area with grafting wax to prevent them from drying out. Check scions throughout the growing season and remove any buds that may sprout. The edges of the scion and the area under the flap of bark contain thin layers of phloem and cambium and if they fuse successfully the flow of food to the roots will be reestablished and hopefully save the tree.
As always, Happy Gardening!
The Purdue Cooperative Extension Service can be reached at 499-6334 in LaGrange Co.