Thursday, June 18, 2015

Summer pruning last year's bark graft.

    Earlier this year, I posted some photos on how I pruned a 2014 bark graft during the dormant season. At that time, I pruned the top portion of the tree to define a strong central leader. Now, three month later, I've returned to that same tree to find the central leader has disappeared again (photo at right).  The top of the tree has become a ball of leaves and branches. The central portion of the new central leader is almost devoid of leaves, while the bottom portion of the tree below the graft is just a mess of brushy growth. This tree illustrates exactly why dormant pruning alone does not ensure good tree form. 
    In summer pruning this tree, I have two objectives--to redefine a central leader and to promote new branch formation in the central portion  of the tree.
    I started at the top of the tree (photo at left). If you look carefully at the photo you can see that I do, indeed, have a central leader but the central leader is suffering from intense competition from rapidly growing lateral branches just below. This is where the 2-foot rule comes into play. I pruned off all lateral branches within the top two feet of the central leader then tip pruned the laterals below that.
    If you look at the lower portion of the stem pictured at left, you can see that there are several buds trying to break that can eventually form branches to fill this naked portion of the trunk. Pruning the top of this tree will actually stimulate these bud to grow out and I'll end up with a more balanced tree.

    The photo at right shows the tree once I finished all my pruning. You can see the central leader once again and I have heavily pruned the brushy growth below the graft union.  Pruning a lot of material off below the graft should stimulate growth of the graft and promote those mid-stem buds to break and form new branches.
    I didn't cut off all the growth below the graft because  a sudden exposure to full sun can cause sunscald on the lower trunk. Once the graft fills out with new branches and those branches start providing some shade to the trunk, I will start removing all branches below the graft union.
   Three of four weeks from now, I'll need to return to this tree for additional summer pruning. I've never met a young pecan tree that didn't need additional directive pruning all through the summer. I'm sure to find some stalked buds ton remove.