Landscape Architect Articles

LCN September 2007 Maintenance Issues08-30-07 | News

Trimming and Pruning Tip Sheet

Pruning cuts should be made in branch tissue just outside the branch bark ridge and collar, without causing injury to the tree. No flush cuts should be made, and no stubs should be left in the tree. It is recommended that cuts do not rip or tear the bark. Photos: UC Davis Operations and Maintenance Department

As you undertake tree-trimming services, there are a number of factors to consider before making the first cut. Important decisions, such as choosing the right time of year to prune and making judicial cuts, will not only impact the health of the trees, but also save time and money and cover you from unnecessary litigation.

Pruning, if done correctly is preventive maintenance, and most of the problems you will face can be solved by nipping improper practices in the proverbial bud. Follow these pruning guidelines to ensure safe and quality work and improve the reputation of your business:

Crown Cleaning

This is the process of removing dry wood and any broken, diseased, or dangerous limbs.

Crown Thinning

Thinning involves the removal of around 25% of the foliage in order to allow for wind passage. This process also increases light penetration through the tree and reduces branch weight. A consequence of removing only inner foliage is an effect known as ?EUR??,,????'??lion tailing,?EUR??,,????'?? where all the growth is situated at the end of branches. This gives the tree an unnatural and unsightly appearance and often results in broken branches.

Crown Raising

Raising is the process of removing the lowermost foliage to provide clearance for vehicles and pedestrians. The minimum clearance is often specified by municipal ordinance.

Crown Reduction

Reduction involves removing larger branches at the top of the tree to reduce its height. When done properly, crown reduction pruning is different from topping because branches are removed immediately above lateral branches, leaving no stubs. Crown reduction is the least desirable pruning practice. It should be done only when absolutely necessary.

To avoid oak wilt disease do not prune oaks during April, May, or June. If oaks are wounded or must be pruned during these months, apply wound dressing to mask the odor of freshly cut wood so the beetles that spread oak wilt will not be attracted to the trees.

Crown Restoration

This is a pruning process done to restore the natural structure after a tree has been improperly trimmed by topping or pollarding.

Timing

It is best to prune most trees in late winter, just before spring growth starts. This exposes fresh wounds for only a short length of time before new growth begins the wound sealing process. Furthermore, it is easier to make pruning decisions without leaves obscuring plant branch structure.

Proper Cuts

No Topping

Topping cuts invite insects and decay and promote profuse watersprout growth.This practice weakens new growth, and depletes trees energy stores.

Inspection

A follow-up tree inspection should be performed after the tree has been trimmed. To cover your firm legally, it is best to comply with the ISA Tree Pruning Guidelines and the ANSI A300 standards.

Compiled from: ?EUR??,,????'??Pruning Trees and Shrubs?EUR??,,????'???EUR??,,????'??+By, Mike Zins and Deborah Brown, University of Minnesota Extension Horticulturists, and the City of Los Angeles Public Works Street Tree Division

Maintenance Details

1/3: A key measurement in the tree pruning world. Contractors should never remove more than 1/3 of a trees crown; they should encourage side branches that form angles that are 1/3 off the vertical; and for most deciduous trees, contractors should not prune up from the bottom any more than 1/3 of the trees total height. Source: Sunshine Nursery and Arboretum