All pruning shall follow the ANSI A300-2001 Pruning Standard and the ISA’s Tree Pruning Guidelines for the purpose of crown cleaning, crown thinning, crown raising, and structure development. 2. All pruning shall improve the appearance of the trees, maintaining the crown shape and symmetry typical of the species at its size and age with an emphasis on the following: 3. Crown cleaning to remove all dead, dying, diseased, crowded, weakly attached and low-vigor branches. 4. Crown thinning to selectively remove and/or prune branches back to large laterals to increase light penetration and air movement through the crown. After crown thinning, trees and branches shall have foliage and mechanical stress evenly distributed along a branch and throughout the crown. 5. Crown raising to remove lower branches where practical to obtain an eventual full foliage height clearance of fourteen (14) feet on the street side of the tree and approximately eight (8) feet on the sidewalk or pedestrian side of the tree. All work shall always maintain the crown shape and symmetry typical of the species being pruned. If a tree is near a building, branches shall be pruned to clear the building by approximately ten (10) feet. Pruning may include heading cuts on lower limbs or thinning cuts to lighten lower branch loads to achieve clearance if complete branch removal is not practical. 6. Pruning for structure such that if a scaffold branch is large in diameter and competes with the leader, that this scaffold branch be headed back to a lateral and/or thinned to obtain a balanced crown shape overall. 7. Pruning to remove all interior crowding branches, and one of all crossed or rubbing branches where practical so the removal thereof will not leave large holes in the general form of the tree. 8. Pruning to remove one branch of all structurally weak “V” crotches occurring along the main trunk or developing within young tree crowns. Special attention shall be given to the effect removal of such branches will have on the ultimate form of the tree. 9. Pruning to remove trunk suckers and water sprouts especially where they are present below the bottomed one half (1/2) of the tree. Such branches that add to the shape of the tree above 14 feet may remain in mature trees which may not have an optimum tree crown or shape.
