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<br />7 <br /> <br />These guidelines establish principles of care and maintenance for the city’s public trees, and are <br />set forth for pruning, planting, watering, soil and nutrient requirements, insect, disease, and fruit <br />control. <br /> <br />A. Restricted Acts to be Avoided without Arborist Approval <br />Restricted maintenance practices for public trees include: <br />1. Excessive pruning , except for clearance pruning of utility lines, traffic or abating a <br />public nuisance. <br />2. Topping. <br />3. Other action that could lead to the death of a tree or could permanently damage its <br />health, including but not limited to cutting, poisoning, over-watering, unauthorized <br />relocation or transportation of a tree, or trenching, excavating, altering the grade, or <br />paving within the dripline area of a tree. <br /> <br />B. Standards for Pruning Public Trees <br />All work on public trees shall be in accordance with the current edition of the following industry <br />standards: ANSI A300 and ANSI Z133. <br /> <br />C. Pruning Methods for Trees <br />There are seven types of pruning that may be appropriate for trees. They are: <br />1. Structural pruning: a type of tree pruning for young trees that establishes a strong <br />central leader and develops subordinate branches. Structural pruning helps to alleviate <br />future failures. <br />2. Crown cleaning: the selective removal of dead, diseased, detached, and broken <br />branches. No live foliage is to be pruned during crown cleaning, and this is the <br />preferred pruning type for mature trees. <br />3. Crown thinning: the selective removal of small live branches to reduce crown density. <br />No more than 25% of live foliage should be removed in a growing season, except for <br />limited exceptions approved by the City arborist. <br />4. Crown raising: the selective removal of branches in order to provide vertical clearance. <br />5. Crown restoration: the selective removal of branches, sprouts and stubs from trees <br />that have been topped. <br />6. Crown reduction: the selective removal of branches and stems to decrease the height <br />and/or spread of a tree. <br />7. Utility pruning: the selective removal of branches and stems to reduce growth away <br />from utility lines. <br /> <br />ANSI A300 (Part 1) Pruning and ISA Best Management Practices Pruning Third Edition should <br />define the pruning method applied as a part routine trimming program. <br /> <br />Pruning may be done outside of the routine trimming program if prune will result in at least one of <br />the following criteria: <br />1. Pruning will result in tree risk mitigation. <br />2. Pruning will result in improved tree structure <br />3. Pruning will establish a dominant leader in a young tree. <br />4. Pruning will provide clearance for new or existing infrastructure. <br /> <br /> <br />Section 3: Routine Tree <br />Maintenance