Thursday, June 20, 2013

Summer pruning last year's bark graft

    During the spring of 2012, I top-worked a large pecan tree.  Earlier this spring, I trimmed the graft union and pruned the tree when it was still dormant.  Last week it was time for summer pruning.
    Like most trees that have been severely cut back for top-working, this tree was sprouting new shoots everywhere (photo at right).  My goal for summer pruning is to remove unwanted shoots and to direct the growth of remaining shoots to help re-establish a strong central leader tree.
    My first step was to cut out all of the sucker growth (photo at left). Already you can see a big difference. The trunk and the graft union are now visible. On all the branches below the graft union, I also removed  suckers that were growing straight up from the upper side of each lower limb. 
    I next turned my attention to trimming back the growth
of the lower branches below the graft.  I cut back these limbs both in height and length (photo at right). These cuts really helped to define the graft as the central leader of this tree.
    Now it was time to turn my summer pruning attention onto the graft. In the photo at left, you can see that the scion is still only about 1/2 the diameter of the stock. This means I need to keep the scion firmly tied to a stake to prevent wind damage. Also notice that the side limbs growing from the scion have all formed nice wide branch angles. That didn't happen by accident. Remember, I removed all the stalked buds from this scion last summer.
       At the top of the scion, the tree has created a profusion of new growth that gives the tree a "lolly-pop" shaped appearance. It time to prune using the 2-foot rule.
      The photos at left shows the branch structure of the "lolly-pop" portion of this tree before (left) and after (right) pruning. I selected one shoot to be the central leader and then removed all other side shoots within two feet of the leader's apex.  Lower side shoots, I left in place especially if they have good branch angles.

     To focus more of the tree's growth energy into the central leader, I tip pruned all lateral branches on the scion below the leader. The photos at right illustrate a lateral shoot before (top) and after (bottom) tip pruning. Whenever I tip prune, I always prune back to a outward growing bud as shown in the photos. 
    After summer pruning, I now have a tree with a clearly defined central leader (photo at left).  However, my work this summer is not done. I'll need to revisit this tree in about 3 weeks to remove any stalked buds and make sure the central leader stays on course.
    You can follow I each step I took last year to apply this graft and to train the scion to become the tree's new top. Here's links to last year's posts.

1. Top working with a bark graft
2. Bark graft bursting
3. Training a new bark graft
4. Summer training a bark graft
5. Painting a bark graft