There are a number of reasons to prune trees. The basic principles are similar for both a deciduous shade tree and a fruit tree. This article will explain the purpose and potential consequence of pruning, describe the difference between thinning cuts and heading cuts, and list the five basic principles of pruning.
The main reasons for pruning a tree are to:
• Promote tree’s health
• Reduce hazards to property and people
• Train a young tree
• Increase or decrease flowers/fruit
Pruning can affect a tree in a number of ways. A couple of things to understand about pruning is that there will be a loss of foliage and the ability for the tree to create food from sunlight. There will be a potential entry point for decay organisms, an increase in sprouting below the cut, and usually increased vigor from remaining branches near the cut.
The optimal time to prune a tree is after the coldest part of the winter has passed and before the sap starts to flow. This allows the tree to endure our usually dry winters and extreme temperature fluctuations that can cause winter stress to trees.
Once you understand the basic principles of tree pruning then you can remove the selected branch based on your desire or need – that is the art of tree pruning. For example, if you want to encourage certain branches to continue to grow up then you will make thinning cuts. By definition, thinning cuts are cutting smaller branches back to existing larger branches. That will encourage more water and nutrients to flow up the branch. If you want to encourage growth to grow out and not up, then you will make heading cuts. By definition, heading cuts are cutting a larger branch back to a smaller branch. Generally, this reduces the height of the tree and promotes growth through smaller lateral branches.
The five principles of tree pruning are simple and basic. They are:
1. If two branches are growing parallel and close together, taking up the same space then one of the branches needs to be cut out of the tree.
2. If two branches are crossed or rubbing, or going to cross or rub, then one of the two branches needs to be cut off the tree.
3. If more than two branches are growing from the same bud then at least one of the branches needs to be cut because that is a weak connection where wind or fruit can break or tear the branch.
4. Whenever you see suckers growing from the base or lower branches cut them out because they are taking water and nutrients away from the normal production process.
5. Always cut out the dead wood from a tree as that can be a vector for disease to enter the tree.
For more information, you can contact your local Cooperative Extension Office in St. Johns, Pinetop or Holbrook. More detailed information can be found at https://extension.arizona.edu/pubs and typing in “pruning.’