Tuesday, August 2, 2016

Mid-summer tree training of newly grafted pecan tree

   During the first summer after grafting a tree, I spent a lot of time pruning and training the scion's new growth to ensure I create a tree with a dominant central leader. The tree pictured at right is an example of a bark graft I made this past spring. I've already pruned the scion down to a single shoot back in late-May and removed stalked buds in mid-June. Looking at the photo, the scion appears to be growing straight and tall just like I want it to grow. However, on closer inspection this tree needs a little attention.  

    My first order of business is to prune off all the trunk sprouts growing below the graft union (photo at left). Its amazing how fast these shoots can grow. If left on the tree,  trunk sprouts can compete with the scion for sunlight, slow the growth of the scion, and retard the callusing over of the graft union.When pruning off these sprouts, I make sure to cut flush with the trunk to help retard regrowth later in the summer.
    Just above the graft union, the tree has started to produce lateral limbs (photo at right). These new shoots are developing from secondary buds along the area of the stem were I had removed all the stalked buds back in June. By leaving all these lateral shoots in place, I'll be encouraging the tree to fill out its canopy well below the central leader. In addition, the leaf area provided by these lateral branches will help strengthen the scion's main stem and increase the tree's ability to capture energy from the sun.

    At the top of the tree I found that numerous stalked buds had started to grow and I was in danger of loosing my central leader (photo at left).  I've seen this kind of brushy top develop on almost every young pecan I've grafted. If I don't re-establish a central leader now, I'll be faced with making even larger pruning cuts next spring.

     I re-established the central leader by removing several competing shoots with a single snip of the hand shears. In the photo above, I've marked the location of my cut with a red line. After the cut is made I'm left with a single shoot to become the new central leader. Below this one cut, I also removed all stalked buds and any shoots that had developed from stalked buds.

    Comparing photos of my tree before and after pruning reveals that the pruning cuts I made had little impact on overall tree appearance (photo at right). But that's the point of frequent summer pruning. I'm directing the tree into growing in ways that with result in good tree structure. Making small cuts now will prevent me from having to make massive corrective pruning cuts in the future.