Frequently Asked Questions



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What is the International Society of Arboriculture (ISA)?

How should I plant my tree?

What is the difference between an arborist and a certified arborist?

Why are trees beneficial?

How to contact the International Society of Arboriculture?

What is pruning a tree?

How to find a certified arborist near by me?

What is topping a tree?

How to find information about tree care?

What is mulching?

How often does my tree need care?

Why should I hire an arborist?

What type of tree should I buy?

Can trees be hazardous?

What should I do if I think my tree has insect and/or disease problems?







A: The International Society of Arboriculture (ISA) was founded in 1924 and has served the tree care industry for over seventy years as a scientific and educational non-profit organization. ISA supports tree care around the world and is dedicated to the care and preservation of shade and ornamental trees. This organization continues to be a dynamic medium through which arborists around the world share their experiences and knowledge for the benefit of society. Aligned on many fronts with other green organizations, ISA is working hard to foster a better understanding of trees and tree care through research and the education of professionals as well as global efforts to inform tree care consumers.


For more information, please visit




A: Arborists are trained professionals that are knowledgeable and equipped to provide proper tree care. They are specially trained to provide a variety to services to maintain trees. ISA Certified Arborists are individuals who have achieved a level of knowledge in the art and science of tree care through at least three years of experience and have passed a comprehensive examination. They are also required to continue their education in order to maintain their certification, ensuring their knowledge is updated on the latest arboriculture techniques. ISA Arborist Certification is a non-governmental voluntary process that operates without mandate of law. It is an internal self-regulating device administered by the International Society of Arboriculture, and therefore, cannot guarantee or assure the quality of performance. Certification provides a measurable assessment of an individual’s knowledge and competence required to provide proper tree care.


To locate an ISA Certified Arborist near you or to obtain additional information, please visit or contact ISA at (217) 355-9411.



A: Trees restore natural harmony in an urban environment, giving scale to human life. Trees are alive, like us, and require an investment and continuous maintenance in order to provide the maximum desired benefits. Some benefits include:


  • Air Filtration― filters out particulate matter and absorbing harmful gases
  • Purifies Water― slows and filters rain water and protects aquifers & watersheds
  • Cost Reduction― reduces yearly heating and cooling costs by 2.1 billion dollars
  • Climate Control― obtained by moderating the effects of sun, wind, and rain
  • Increase Property Value― well-cared landscape properties are 5-20% more valuable than non-landscaped estates.

For a healthy and long life, trees need the proper maintenance. Therefore, in order to provide proper tree care, you should refer to a certified arborist.

For more information on why hiring an arborist, please visit



A: To find an ISA Certified Arborist near you, please visit and type in your zip code to obtain a list of certified arborists in your area. If you do not have access to the internet, you may contact ISA at (217) 355-9411 to have a list mailed to you.




A: You may obtain additional information from your local ISA Certified Arborist, tree care professional, garden center, community forester, etc. by referring to your local yellow pages or visiting this site for a wide-range of tree-related topics.



A: Trees provide a variety of benefits besides environmental, such as social, community, and economic. Trees provide an array of benefits, including:


  • Cost Reduction― reduces yearly heating and cooling costs by 2.1 billion dollars
  • Increase Property Value― well-cared landscape properties are 5-20% more valuable than non-landscaped estates.
  • Privacy and Scenery, aesthetic values

The following facts are results from studies conducted by UIUC Human-Environment Research Laboratory:

  • Fewer Crimes― apartment buildings surrounded by trees and greenery are dramatically safer than buildings devoid of green
  • Improves Concentration- children with Attention Deficit Disorder (ADD) are relieved after contact with nature. The greener the setting, the more the relief.
  • Sound Barrier- acts as sound barriers and provide protection against crowding, noise, and danger, which all can contribute to mental fatigue, and can help inner-city residents cope with the many poverty related-stresses

For more information on the benefits of trees, please visit and



A: Tree selection is one of the most important investment decisions for a homeowner. First, examine the location conditions of where you want your tree to be planted. Take the following into consideration before selecting the tree species you want:


  • Amount of space
  • Clearance from overhead and underground utilities
  • Weather conditions
  • Tree functions you desire
  • Exposure to sun and wind
  • The quality

Then, utilize the information you have gathered and select the tree species that works best with the conditions. For assistance, contact your local ISA Certified Arborist, tree care professional, or garden center to plant the right tree in the right place.

For more information on selecting and purchasing trees, please visit and


A: Location conditions are extremely important and vital to a tree’s health. Be sure to examine the tree location conditions and follow these steps when planting your new tree:


  • Dig a shallow, broad hole: only as deep at the root ball, but 3x’s as wide in diameter
  • Identify the trunk flare: this is where the roots spread at the base of the tree. This should be partly visible after planting.
  • Place the tree at the proper height: majority of the roots should be within 12” of the soil.
  • Straighten the tree in the hole
  • Fill hole, gently but firmly
  • Stake the tree, if necessary
  • Mulch the base of the tree
  • Maintain with follow-up care

For more information on tree planting, please visit



A: The type and frequency of tree care depends on the species, age, location, climate, and other factors that affect the tree’s growth. The first step is to educate yourself about your trees and understand their needs. It is imperative to understand that proper tree care is a life long process, and that planting and caring for a tree is a long-tern commitment, not just a one time deal. Contact your local tree care professional for proper assistance.


For more information on proper tree care, please visit for a wide-range of quality arboriculture information.



A: Pruning is the cutting or removing branches or parts of trees or for improving the shape or growth of trees. This is the most common tree maintenance procedure. Usually, trees are pruned preventative or as a corrective measure to remove dead branches, crowded or rubbing limbs, eliminate hazards, and increase light and air penetration. Since each cut to a tree has the potential to change the growth, it is important to educate yourself, considering no branch should be removed without any reason.

or more information on pruning the proper techniques, please visit for young trees and for mature trees.





A: Topping is the indiscriminate cutting of tree branches to stubs or lateral branches that are not large enough to assume the terminal role. Other names for topping including “heading,” “tipping,” “hat-racking,” and “rounding over.”

Topping is perhaps the most harmful tree pruning practice known. It is usually done to reduce the size of a tree. Often, homeowners top their trees because they feel that they have become too large for their property and are a hazard. However, topping will make a tree more hazardous in the long term and is very harmful to the health of a tree.

For more information on topping, visit



A: Mulches are materials placed over the soil surface to maintain moisture. Mulching is extremely beneficial to trees. It can reduce water loss from soil, minimize weed competition, and improve soil structure. Properly applied, mulch gives landscapes a health dose of benefits for your trees.


For more information on proper mulching techniques, please visit .




A: As soon as you notice any abnormality in your tree’s appearance, you should begin a careful examination of the problem. Insects and diseases can threaten a tree’s health. By identifying the specific symptoms of damage and understanding the causes, you may be able to diagnose the problem and take appropriate actions for treatment. You should contact a tree care professional for assistance immediately.


For more information on insect and/or disease symptoms, diagnosis, causes, and treatment, please visit .




A: Trees are essential to our world, offering a wide range of benefits to our environment. However, trees become hazardous liabilities if they fall and injure people or damage property. Proper constant maintenance will help prevent and identify when a tree becomes dangerous. Evaluating the seriousness of a trees condition is best done by a professional ISA Certified Arborist.


For more information and tips for identifying hazardous trees and its defects, please visit





A: Please contact ISA to obtain additional information on arboriculture (tree care) related topics. We will be happy to assist you!


International Society of Arboriculture
P.O. Box 3129
Champaign, IL 61826-3129, USA
Phone: (217) 355-9411
Fax: (217) 355-9516











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