 A utility must have practices in place for tree pruning similar to methods prescribed by Dr. Alex L. Shigo and keeping in compliance with ANSI A300 that include avoiding tree topping, tree tipping, removing branch collars and leaving long stubs.Workers who perform line clearance, including contractor workers, must read and understand Dr. Shigo's field guide (or an equivalent one approved by the State Forester and the Foundation), follows its recommendations, and has a copy at every work site for quick reference.For trenching and tunneling near trees, it is recommended workers follow methods in Dr. James R. Fazio's field guide to reduce the destruction of roots and injury to trees.