With all the snow melted and temperatures in the low 70's (F), I spent this past weekend pruning trees in our pecan breeding block. I do most of my trimming with a chain saw. I use the nose of the blade to plunge cut limbs off at just the right angle as to leave the smallest possible wound. The pair of photos above shows the textbook case of a branch attached to the trees with a pronounced branch collar. To remove this branch, I approached the limb from the side holding the chainsaw's blade at the same angle as the branch collar. I then plunged the nose of the chainsaw into the branch, cutting it off quickly and cleanly. Note that the branch collar is still present and the pruning wound is minimized.
When working out in the field, you'll find that nature doesn't always follow the illustrations in textbooks. In the photos at left you will note that this lower limb is attached to the trunk without a prominent branch collar. In this case, you can see a partially formed branch collar on the upper side of the branch attachment but the collar is non existent along the side of the branch. I just had to pick an angle and plunge cut away. Was it the right angle? It looks good to me and I'm glad I removed this limb before the apparent bark inclusion seen in the photos became a major problem.
Sometimes a tree can provide you with multiple pruning challenges. In the photo at right you can see I was faced with the typical forked tree, but this tree also had a small limb growing at a right angle from the fork. The pecan in the photo was placed in the tree's fork by a bird, storing away the nut for a late winter snack. My ultimate goal for pruning this tree to to remove the fork and encourage the development a single trunk. Pruning this tree required two steps. First, I removed the small side branch and cut the weight off one half the tree (above). Pruning off the weight helps prevent bark tearing.
To complete the pruning of this tree, I needed to remove the stump I left after pruning off most of one side of a tree's fork. In the photo at right you can see the well developed bark inclusion and the total lack of a branch collar. At this point I just picked an angle that looked right (this is definitely an art) and plunge cut off the stump.
And if you are wondering, the pecan tasted pretty good!