Thursday, February 16, 2017

Pecan tree limb pruning and collecting scions

    On a mild sunny days in February, its hard for me to stay indoors when there are pecan trees to prune and scionwood to collect. When approaching a young tree, like the one pictured at right, I confine my pruning efforts to removing low limbs and removing serious structural problems. And, because I'm pruning young trees, the limbs I cut off usually produce some excellent scionwood. Let me take you through the process. 

    I started by removing the lowest limb on the left side of the tree pictured above. When removing low limbs, always cut back to the trunk but make that cut outside the branch bark collar.
    The photo above shows the tree before and after pruning. The side limb I removed looks like it was growing out of a socket in the main trunk. The raised bark area on the trunk that forms that socket is what we call the branch bark collar. I plunged the blade of my chainsaw into the side of the limb just outside the collar and dropped the limb off the tree. Leaving the branch collar intact will help the tree quickly heal over the wound.

    I moved over to the other side of the tree to prune off the next lowest limb on the tree. With this limb, the branch bark collar is not so obvious. In the photo at right you can see a slight swelling of the bark around the limb where it attaches to the trunk. The place to prune off the limb is marked by the red dashed line. The final cut is shown on the far right.

    My goal in pruning off lower limbs is to make working around the tree easier. In the photo at right, you can see that removing just two limbs makes a big difference in terms of improving access for orchard operations like mowing, herbicide application and harvest.

    Besides cutting off lower limbs, my dormant season pruning routine also includes looking for potential structural problems. One common problem is the development of a V crotch (circled in yellow in photo at right). Left to grow, a V crotch will form a bark inclusion between the two branches increasing the likelihood of branch tear out. So while the tree is still relatively small, I reached up and cut off one of the two branches that had formed the V.  After taking out the V crotch the tree might look unbalanced but it will quickly fill the open space in the canopy with new shoot growth.

    I also look to remove branches with narrow crotch angles and deep bark inclusions. The method I use to cut out these narrow angled branches depends on the size of the limb. Previously, I showed you how I cut out a larger limb using the three cut method. With the 2.5 inch side limb pictured above I made just 2 cuts. The first cut I made was and undercut about 1/3 the way through the branch. I made this cut at an angle that would promote rapid wound healing. Next I used the chainsaw to plunge cut into the side of the limb to remove the limb.

    The young trees I pruned were growing rapidly so the branched I removed held many one-year-old shoots that were over 2 feet long.  Before hauling the pruned limbs off to the brush pile, I cut off any shoot that wase 3/8 inch or larger in diameter. Some of the wood I collected is shown at right.

    In collecting scions, make sure to collect only last year's shoot growth. Sometimes on young trees its a little difficult to tell where 2-year wood stops and 1-year wood begins. In the photo at left, the yellow arrow points to the annual growth ring which is the point on a shoot that marks the beginning of a new shoot growth year. Above the growth ring is 1-year wood. Note the large primary buds on the 1-year shoots. Below the growth ring is 2-year wood. Note that the primary buds on 2-year wood are gone. They either dropped off the tree or sprouted last year to produce catkins. Either way scionwood without strong buds is useless.

   In cutting scions, I usually cut the wood into 7 to 8 inch long pieces, making sure I have at least 2 good buds on the upper half of the scion. In cutting up the wood, I also like to make sure the lower half of the scion is straight. Looking at the shoot pictured at above I noticed a strong curve at the base of the shoot. I cut off the curved portion of the shoot and discarded it. Right above the curve I cut out a perfect piece of Kanza scion. 

    In cutting scions, I also look for scars or imperfections in the wood. Since I'm collecting scions from low limbs, I find that some branches get banged up by the tractor when I mow the orchard. I always cut out imperfections like one pictured at left. There is usually plenty of good scions to be found above and below such a branch wound.