ANSI A300 Standards for the Tree Care Industry Parts 1-3: Pruning, Soil Management, and Supplemental Support Systems
The tree care industry has its own set of voluntary consensus standards called the ANSI A300 standards. They are generally accepted to be the industry standards for tree care practices. Each of the A300 standards are developed by the Tree Care Industry Association (TCIA), an ANSI-accredited Developing Organization (SDO), and written by a committee called the Accredited Standards Committee (ASC) A300, a group comprised of industry representatives.
The ANSI A300 standards are divided into nine parts, each focused on a particular aspect of tree care. This article examines the first three parts, which focus on pruning and trimming operations, soil management, and supplemental support systems.
ANSI A300 Standards (Part 1) – Pruning & Trimming Operations
Part one of the A300 standards addresses pruning practices, pruning objectives, pruning methods, palm pruning, and utility pruning.
The four basic pruning methods recommended by the A300 pruning standards are:
- Cleaning: The selective removal of dead, diseased, or broken branches.
- Thinning: Selective pruning intended to reduce crown density.
- Raising: Selective pruning of lower branches to provide vertical clearance.
- Crown Reduction: Selective pruning to reduce a tree’s height, or crown density.
- The A300 pruning standards advise against practices such as tree topping, lion’s tailing, and rooster tailing.
ANSI A300 Standards (Part 2) – Soil Management
Part two of the A300 standards encompasses soil management. It establishes voluntary standards for soil management under three subsections: soil modification, fertilization, and drainage.
Under the modification section, part two of the A300 standards examines how to properly evaluate the condition of soil, how to manage organic matter in soil, how to incorporate soil amendments, and how to apply organic mulch to the surface of a soil site. The modification section also explores prevention and mitigation practices for soil compaction.
The fertilization section assesses the impact of pH adjustments on soil. It also describes fertilization practices, recommended methods of application, and calculations for fertilizer amounts.
The fertilization methods recognized under the fertilization section are:
- Surface Fertilization: The application of dry fertilizer on the soil surface.
- Subsurface Dry Fertilization: The application of dry fertilizer below the soil surface.
- Subsurface Liquid Fertilizer Injection: The application of liquid fertilizer below the soil surface.
- Spray Applications: The practice of spraying a liquid directly on the foliage.
- Liquid Plant Injection: Injecting a liquid directly into the plant.
- Implant Fertilization: The process of implanting a solid directly into the plant.
The drainage section of the A300 standards discusses the mitigation of impenetrable soil layers, as well as the mitigation and adjustment of surface drainage, and subsurface drainage. As a general rule, the drainage section advises against surface applications where surface runoff is likely to occur.
ANSI A300 Standards (Part 3) – Supplemental Support Systems
Part three of the A300 standards applies to installation and maintenance of tree support systems, including cabling, bracing, guying, and propping.
The subjects it examines are:
- Tools and equipment used for performing support system installations.
- The objectives of cabling, bracing, and guying.
- The types of cabling systems and bracing techniques recommended for use.
- Guying methods, including tree-to-ground guying and tree-to-tree guying.
- Propping procedures for trees and branches.
- Each subject is accompanied by a series of tables that describe hardware sizing and selection.
The A300 Supplemental Support Systems standards recommend four basic cabling methods:
- Direct cabling consists of a single cable installed between two sections of a tree. Cables can be installed between two limbs, two stems, or a trunk and a limb.
- Triangular cabling involves connecting sections of a tree in combinations of threes. This method is ideal for providing trees with maximum support.
- Box cabling is when four or more sections of a tree are connected together in a closed series. This method should only be used when minimal direct support is required.
- Hub and spoke cabling consists of a hub that acts as a center attachment with spans of cable radiating to three or more leaders. Hub and spoke cabling should only be used when no other cabling system is deemed viable.
- According to the A300 standards, supplemental support systems should receive periodic inspections by an arborist.
- Trees may displace cabling systems as they continue to grow. If cables are not located two thirds of the way up the tree, the A300 standards recommend updating the system.
- Supplemental support systems do not provide primary support to a tree. Their purpose is to provide trees with additional support, or restrict their movement.