Trees are valuable resources and deserve to have professional care. To find a certified arborist, you can visit the following website: www.treesaregood.org. This site allows you to search for certified arborists in your area. The site also contains a lot of information on tree care.
Most of the established local tree service companies have arborists on their staff. Some of the larger nurseries in Orange County have ISA-certified arborists on staff. You can verify that an arborist is certified by visiting the above site.
We encourage you to comment below on any positive experiences you have with an individual arborist or tree service company. This will help us to be of even greater assistance to the gardening public in Orange County.