Pruning is basically cutting the branches of a tree to give it a desired shape to allow all leaves to have good sun, to make the harvest easier and some times induce shock to make the tree grow faster.
Pruning requires good understanding about tree forms, their innate repair mechanisms and should be done with proper tools and by trained arborists to cause least damage to the tree.
We were always skeptical, of course, whether pruning is really necessary. It seemed too much human intervention in a tree’s life to make it grow better. Again our belief has been that no matter how much we study, we will only know so much that we can perceive. It would be best then, to let nature take its course and let the tree grow how it is supposed to. The branches of a growing tree follow the sun so that the leaves can make food for the tree. A naturally growing tree can take care of the right spacing between branches/leaves.
The problem is that the most of the trees you will plant will be from a nursery where they have been transplanted from seed trays, small bags to big bags at least a couple of times. When a tree grows in a nursery bag, the roots have a limited space to look for their food. Also, the nursery soil medium being rich, gets the roots used to easy access to food. Thus, the roots don’t develop a robust system. This impacts the tree’s growth above the ground, even after it is transplanted in the earth. Moreover, how the tree was put in the ground also impacts the rest of the tree’s life.
With so many things to take care of and involving human hand, deviations from ideal are bound to happen. Also there is no clear understanding of the ideal. Even trained experts have conflicting opinions and it is often a trial and error until you find what works best in your context.
Although, once you start pruning and influencing the growth and form of the tree, the tree will react unnaturally and more pruning will be required over time. So the idea would be, if a tree were planted directly from the seed in the ground, it will naturally grow into the best form possible, if no human intervenes.
Time for Pruning
For deciduous trees (trees which shed their leaves before winter), pruning after the leaves are gone and the tree is dormant would be least stressing to the tree. Also this will help the tree cope, once the spring arrives, with new flushes of leaves.
In most evergreen trees, pruning is done for corrective reasons so seasonal timing is not very important. However, pruning during dormancy (before spring) would again be advisable.
At sun farm, we have about a hundred 3-4 years old pear trees. They were bought from a nursery or grafted onto another hardy pear variety. They havent been pruned/thinned properly in the past years. We wanted to prune some of these trees to see what effect it has as compared to the trees which were not pruned. We pruned half of the young pear trees, pruning one and leaving one so that an assessment on tree health can be made over a few years.
After some research and consultation, we agreed on an central leader, open centre, wine glass form for the pear trees.
Some basic pruning would involve:
Topping is cutting back of the main vertical stem or other branches to stubs to reduce the size of the tree. This is done to obtain a desirable shape of the tree, making it easier to harvest from or in some cases to prevent the tree from growing too tall and posing a risk of falling.
- Removing water sprouts
These are branches that grow from the latent buds on the main stem or old branches often to cope with stress or as a response to pruning. Water sprouts are undesirable because they are susceptible to diseases and produce very little fruit, if at all.
- Removing suckers
Suckers are shoots that grow from the root of the tree at a distance from the main stem. Suckers are undesirable as they will always compete with your tree for water and nutrients in soil and the sun, if allowed to grow bigger.
- Removing the dead, diseased and broken branches.
- Removing one of the branches when two branches are growing into each other, rubbing against each other.
- Removing the branches growing inwards (towards the centre of the tree).
The right cut
The cut has to be made such that the bark doesn’t peel off from below the cut. Often this wil require first a partial cut below the branch at the collar and then a full cut from the above. The second and final cut should be at an angle of 45 degrees just above the branch collar.
It is important to note that the place where the cut has been made is a potential entry point for pathogens and cause extensive decay in the tree. Here we covered the pruning wounds with cow-dung to prevent this.
From this it is clear that pruning is a vicious cycle. Pruning will cause stress which will force the tree to send out more water sprouts, suckers and grow in an unnatural form. This will require more pruning over the years.
We pruned these trees based on the experiences shared by experts and locals and some of our own understanding. Each tree is unique and it took us some time with every tree to imagine various possibilities before using the saw/scissors.
Update on March 1st, 2016
After nearly a month of pruning, we observed the new shoots at the pear trees coming from off from the stumps of the branches that were cut back.
This would mean these branches will again have to be cut next season.