Arborists go through extensive training and testing.  A well-trained, credentialed arborist knows how to treat diseases or remove damaged limbs to maintain a tree for its health, not just for aesthetics.
Your tree took decades to grow, but a few minutes in the hands of an amateur can disfigure it. Or you may spend money treating the wrong problem.
Only a good arborist, like those at Trees "R" Us, Inc. can identify and treat diseases or pests, add bracing to large branches or add lightning protection to trees overhanging your home.  In addition the arborist should be able to show you the proper way to mulch the tree and even protect the roots during an upcoming construction project, such as a room addition or new walkway.
When looking to hire an arborist, of course I would tell you to call Trees "R" Us, Inc. first.  But, if you aren't living on the North Shore or in the Chicagoland area, you should try to find an arborist that has credentials from the International Society of Arboriculture (ISA) (isa-arbor.com) or its Illinois chapter (illinoisarborist.org). Credentialed arborists must take education courses to maintain their certifications.  I've been through these classes firsthand and it is no easy task.  Credentialed arborists and the most highly qualified tree care professionals you can find. 
At Trees "R" Us, Inc. we take our credentials a step further.  an arborist who climbs trees is the gold standard. They are becoming rare to find. But it's beneficial when the person doing the work can get up in the tree to see the problems up close.  Here are Trees "R" Us, Inc. we do just that.  We pride ourselves on quality and comprehensive tree care.  The only way to accomplish that is to get  up close and up high!
North Shore residents and those in the north and northwest Chicago suburbs have been turning to Trees "R" Us, Inc. for nearly 20 years. You can trust your trees to Trees "R" Us, Inc.  Visit us on the web at www.treesrusinc.com or call us at 847-913-9069.

Thanks for reading,
Nick
nick@treesrusinc.com