COMMUNITY VOICES: Post Arbor Day tree tips

May 5, 2012 by  
Filed under Solar Energy Tips

Arbor Day has come and gone, and maybe you have a new tree to care for. Now what?

There are some very important things to do to help establish a young tree and prepare it for a long life.

Watering and training are two keys to tree establishment.
Watering a newly planted tree is important because much of its root system was left behind. As much as 90 percent of a tree’s roots can be left at the nursery when they are dug with a tree spade. Other methods of moving trees such as bare root or containerized will preserve more of the roots, but they will also need supplemental watering.

Typically, if it does not rain in a week, it is beneficial to slowly soak the root ball of a 2” caliper tree with about twenty gallons of water. Bigger trees will require more water, and they have probably lost a proportionately higher volume of their root system. This is necessary for at least the first year following transplant while the tree is regenerating roots.

Mulch can help or hurt. A two inch deep layer of mulch out past the root ball can help. Deeper “volcano mulching” can actually prevent water from reaching the root ball and is detrimental in other ways. It should never be piled up against the trunk, keep it a few inches away. Wider is better, deeper is bad. I see over-mulching all too often and it not only hinders tree establishment it is also a waste of money. So mulching is related to watering, it can help keep soil moist near the root ball if properly done, or it can prevent sufficient water from reaching the roots if applied too deeply. Two to four inches is good, more than that violates the national standards for tree planting.

Training is the other activity that is critical to a long-lived tree. This is specialty pruning of a young tree for structure and form. Training can start after the first growing season following transplant. In that first year, it is best only to remove the three “Ds”; dead, diseased, or damaged branches. This way the tree has maximum ability to photosynthesize and produce roots from energy it gets from the sun. Trees do not need to be fed; they produce their own sugars from solar energy.

After that first year, and the roots are growing, training for structure can begin. Narrow crotch angles form weaker branch unions than wide angles, such as a branch extending at right angle (90 degrees) from the trunk. Narrow crotches and competing vertical stems (co-dominant leaders) can form included bark, a weak area where bark exists trapped inside the union.

Co-dominant stems that have bark trapped inside the union are significantly weaker than those that do not have bark included. This weakness is relatively more pronounced in smaller branches, as in young trees. It is frequently where a tree will fail under stress, but training can eliminate this structural weakness.

When we train a young tree, we look for radial symmetry.

Branches should be spaced out symmetrically around the trunk as viewed from above. Perhaps more importantly, trees should be trained for proper scaffolding. Except for trees that naturally have whorls of branches like spruces and firs, branches should be form a staggered scaffold going up the trunk. Branches should be spaced appropriately with vertical separation. When multiple branches extend from the same point in the trunk, it can become a future problem and result in branch failure. Again, included bark is often the reason for this failure.

The national standards for tree pruning indicate that you should never remove more than one third of the tree’s photosynthetic ability in any growing season. With older or stressed trees, this should be reduced to no more than one quarter of the branches. This means that training young trees may take several seasons to accomplish.

The importance of training young trees was recently demonstrated by a late spring snowfall in upstate New York.

The trees were flowering and leafing out, so they held a lot of the heavy, wet snow. As the weight accumulated, branches failed and many young trees suffered damage. Almost all of the damage I observed occurred at weak branch unions that had included bark. Training for structure could have prevented this damage by eliminating the weak structure. We simply pick one of the competing branches to retain and properly prune the other.

Correct pruning technique is another whole topic. Very basically, prune at the branch collar. Do not leave stubs and do not make a flush cut. When training a young tree, a simple snip with hand pruners can avoid a big saw cut later
and potentially avoid a future branch failure.

Remember: water your tree in dry spells as it generates new roots. With mulch, wider is better. Never pile up mulch in volcano like cones against the trunk. Remove only dead, damaged, or diseased branches in the first growing season.

After that, you can begin training for structure and form. Never remove more than a third of the crown in any one season. It is better to stay on the conservative side when practical and only remove up to one quarter of the leaves. These are the trees solar panels and produce the food necessary for growth.

Do all this and you will give your new tree a great start!       

Andrew Hillman is an urban forester on contract with the city of Fall River through a Mass. DCR grant. Community Voices is a weekly column featuring community-based experts or specialists.

Comments are closed.