Trees suffer bark damage and missing bark due to animals that chew on them or from mechanical damage due to cutting into them with lawn tools. The phloem tissue layer under the bark is responsible for carrying nutrients to the roots and other parts of the plant. Bridge grafting is the process of cutting, preparing and installing pieces of bark and wood vertically to connect the bark above and below the damaged area and allow the nutrients and water to bridge the gap.
Measure the height of the bark damage vertically from the top to the bottom of the section where bark is missing with a cloth measuring tape. Measure the length of the bark damage around the tree horizontally.
Cut sections of bark and underlying wood (scions) in the winter with a utility knife from young branches on the same tree about 3/8 inch in diameter and the height of the bark damage's measurement plus 5 inches. Cut enough scions to place them about 2 inches apart around the damaged area. Mark each scion with a dot with a permanent marker at the top of the scion.
Place the scions in a plastic bag and insert a damp paper towel into the bag. Place the bag into a refrigerator set to 34 degrees Fahrenheit until the spring.
Trim the bark damage with a utility knife above and below the missing bark horizontally in the spring when new growth is appearing on trees. Trim loose and dry bark from around the wound. Remove the scions from the refrigerator.
Make two slits about 1 1/2 inches long in the healthy bark above and below the missing bark the same width apart as your scions' diameter. Pry the bark in between the slits to form a small flap at the top and bottom.
Hold a scion up to the flaps and trim it on the ends to a length of 4 inches longer than the missing bark height. Cut both ends vertically at a 45-degree angle to make a point on the ends.
Insert the top tip of the scion with the permanent marker dot under the top flap of bark. Insert a pencil under the center underneath the scion and tuck the bottom into the bottom bark flap.
Place a 1-inch brad on the top flap and pound it into the flap with a rubber mallet. Attach the scion in the bottom flap in the same manner as the top. Remove the pencil and continue adding scions in the same manner as the first around the damaged area, spacing them about 2 inches apart.
Place hand-grafting wax in one hand and rub it with your other to warm it and make it pliable. Press the wax over the flaps, scions and all exposed areas between the scions that have bark missing in a layer about 1/2 inch thick.