Monday, March 18, 2013

Co-dominant Leaders

Co-dominant leaders are commonly found in ornamental trees that are planted in urban landscapes. Because urban trees have no need to grow straight up to gather light, these trees grow up and out and every branch has an equal chance to gain dominance. Dominant branches that are not found in the center of a tree can cause problems as the tree matures. Co-dominant leaders can also develop included bark as the leaders grow together. 

The following image shows two leaders that are equally dominant. These leaders are not a problem now, but this tree is still very young. Imagine what this tree will look like when the trunk is over a foot in diameter and these leaders have grown together.

Co-dominant Leaders Left Unchecked Will Result in More Significant Fruit Tree Problems in the Future
Because this tree is still young it is a great time to fix it. Removing one of the leaders may cause the tree to appear lopsided and bare on one side. Significantly decreasing the smaller lateral branches of one leader will decrease the amount of leaves in the summer. This will decrease the amount of energy collected and slow the growth of this leader. When the second leader has regained dominance, and the tree has increased it's overall size, removing one of the leaders will cause less stress and be less visually damaging to the tree.

The following is an image of a tree that has been pruned to help the central branch gain dominance.

Re-establishing a Strong Leader May Take Several Years

Notice that the branch on the right side of the image has a wider diameter than the one in the middle. Many of the branches that were growing toward the center of the tree were removed to slow the growth of the right branch and to allow more light to the center branch. In time the center branch will obtain dominance and the overall health and appearance of the tree will improve.

Fruit trees are different than ornamental trees in that the leader is completely removed. A fruit tree with an open center is like a tree with multiple leaders, but they are spread far enough apart that they don't grow together like ornamental trees. You will need to treat each of your main fruit tree branches as if they are separate leaders. Co-dominance can occur in one or many of the main fruit tree branches and pruning is necessary to avoid included bark and weak crotches.
 
For more information regarding the pruning terms used in this post, visit our pruning page here.