Usually trees and shrubs will get most of the nutrients they need from the fertilizer that is put on the lawn. Yet, this means that the lawn will be losing some of the nutrients that it needs to grow and be healthy. Fertilizing trees and shrubs ensures that both they and the lawn get all the nutrients that are required. 

Trees and shrubs planted next to drive-ways or sidewalks naturally can't get any nutrients through the concrete or asphalt. This can give rise to deficiencies that will be compensated for by fertilizing. 

Keep Your Trees Healthy
Insects can defoliate a whole tree. Unsightly fungus or mildew may detract from an otherwise beautiful tree. These are two problems that need prevention rather than cure. Once the problem has been spotted it's often too late. Your lawn care professional can eliminate these problems by spraying your trees before infestation. They will also be up-to-date on any infestations that are occurring in your area.

In colder climates dormant oil can be applied in the fall. This will help to avoid damage to your trees by helping to control insects that try to over-winter in them.