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Monday, May 4, 2020

Regrafting a damaged tree with an arrowhead graft

   Last summer, I discovered that one of my grafted trees was girdled by a squirrel stripping the bark from the fast growing scion (see Here). After cutting out the dead graft, I allowed one shoot to grow from the trunk  beneath the old graft union. As that shoot grew, I used an eight-foot-long wooden stake to train the fast-growing stem into the tree's new central leader (photo at right). Now this Spring, its time to re-graft the tree.
    My first step was to trim off the dead wood above the point where the new shoot emerged from the trunk (photo at left). When making the cut, I followed the obvious line marked by the shrinkage of dead bark tissue. The resulting angled cut should allow the tree to heal over the wound as quickly as possible.

  
    To prepare the tree for grafting, I cut off the top of the new shoot and inspected the size and shape of the stock as compared to the size of my scion (photo at right). The stock was fairly small and very round. This called for an Arrowhead graft. 
     The first cut in carving the scion for this graft is very deep, leaving only a thin tongue of wood (photo at left).
    Next, I turn the scion over onto the bark side and carve both edges down to reveal cambium tissue (photo at right). My final cut on the scion is to create a chisel point at the tip to ease its insertion under the bark of the stock.

   With the Arrowhead graft, the scion is inserted between the bark and the wood right down the middle of a slice made into the stock's bark (photo at left). As you push down on the scion, you should see both sides of the bark pull up to cover the cut surfaces of the scion. The long thin strip of bark left on the back side of the scion should stay in the middle and be visible in the bark crack.
    To ensure good cambial contact between the scion and the bark of the stock, I place a row of staples vertically to bend the bark to conform to the shape of the scion (photo at right). These stables do not pass through the scion, they are placed right next to the scion causing the bark to bend noticeably inward.
    Since the staples are not actually holding the scion firmly in place, I wrap the graft union with grafting tape to make sure the scion can't move (photo at left).  I then cover the graft with aluminum foil and a plastic bag to block out the sun and hold in moisture.
   What a squirrel destroyed last year, I've made a good start rebuilding this year.  I replaced the 8 foot stake fully expecting this graft to take off (photo at right). I also put a deer cage around the graft to ensure against browsing  injury.