Spring cleaning

 

    During the rush of harvest there seems little time to clean up fallen limbs and other grove debris. Sure most growers run a stick rake over their groves before harvest, but the piles of sticks and grass remain in the grove all winter long while we concentrate on nut harvest. With the onset of nice spring weather, its time to clean up pre-harvest stick piles and collect even more wood that fell out of the trees over the winter. In the photo above, a stick rake (on the right) is being used to collect the wood that has fallen since harvest and a skid-steer (on left) works to pile the collected wood on a burn pile (note the smoke). 

      It is important to get your brush piles burned as soon as possible. With all that nitrogen fertilizer we apply to native pecans, the ground cover is really growing. It won't be too long until the grass hides chunks of fallen limbs that can rattle both you and your brush hog.

Native pecans in early spring

 

"In every man's heart there is a secret nerve that answers to the vibrations of beauty."

  ~Christopher Morley, 20th century poet and author

 
    As spring growth emerges from our native pecan trees, the grove is carpeted by the pale flowers of blue phlox, Phlox divaricata. In every season of the year, nothing calms the spirit like being immersed in a native pecan grove.

Pecan tree growth patterns

    Pruning pecan trees can be frustrating. Every spring when you go out to look at your young trees you find 2 to 3 limbs growing every which way but straight up. So you hack away at the tree hoping to create a tree with a strong central leader. The young tree pictured at left is typical--4 limbs all growing from the same general area. Two of the limbs look like they want to be the dominate central leader.
    To prune this tree, I would cut out one of the two upright growing limbs. Leave the limb on the southern side if possible. The second limb I'd remove is the right-hand branch because of its narrow crotch angle. I'd leave the obviously, less-vigorous left-hand branch alone.

    Pruning is made a lot easier if you come to understand why pecan trees grow the way they do. As your trees start to leaf out this spring, take a close look at the terminal growth (photo at right). Believe it or not, pecan has strong apical dominance. Notice how the very top of the tree has already developed new shoots while the buds further down the stem are just starting to pop. As the top of the tree grows, the leaves manufacture a plant hormone that sends a chemical message down the stem to suppress the growth of lower buds.

     Now take a closer look at the emerging new growth (photo at right). I count 4 new shoots all coming from the top 2 inches of last-year's wood.  Leave this cluster of new shoots to grow for the entire growing season and you will end up with the same pruning chore pictured at the beginning of this post, but only two feet higher in the tree.
     You can save a lot of pruning time by addressing this growth pattern early in the growing season. Once the new shoots have grown out about 6 inches, I prune the top to a single new shoot. The easiest way to do that is to locate the lowest shoot in the cluster of shoots and then cut off the stem just above that new shoot (see related post). This removes all the competing shoots above that point and you should be left with one 6 inch shoot that will grow to become your central leader.

Anatomy of a Bark Graft

    Ever stop to think about how truly amazing the process of grafting is? A seedling tree accepts a scion then pushes it to grow a whole new tree crown. I've been grafting for over 30 years but I still stop to marvel when buds start to push on a newly placed scion.
    Recently, I cut down a tree that had been bark grafted five years ago. I wanted to learn a little about the anatomy of a successful graft. After cutting the graft union from the rest of the tree, I used a band saw to slice open the wood. The photo at left shows what the band saw revealed.
     You can immediately see the top of the original stock tree (marked A) that had been trimmed at an angle to promote healing. Also, note the top of the original scion buried under years of wood growth (marked B). This cross section of a graft clearly demonstrates that trees never really heal their wounds, they just grow new wood over the damaged tissue.
    In any orchard of grafted pecan trees, it is usually pretty easy to see a change in bark texture associated with the graft union. Genetic differences between rootstock and scion are also noticeable in the wood. You can see a clear line (marked C) across this tree's trunk that marks the change from rootstock to scion cultivar. Note the line runs nearly straight across the tree at a point where the top of the stock meets the bottom of the scion. The strong dip in the line (marked D) is actually part of the original scion that was slipped under the bark during the grafting process.