SECTION 02930 - EXTERIOR PLANTS/TREES

PART 1 - GENERAL

1.1. Unless otherwise noted, illustrations are by Edward F. Gilman, Professor, Environmental Horticulture Department, IFAS, University of Florida; adaptions from Arboriculture: Integrated Management of Landscape Trees, Shrubs and Vines, 4th ed., by R. W. Harris, J. R. Clark, and N. P. Matheny (Prentice Hall, 2003).

1.2. Where specifications herein conflict with Lancaster Tree Manual guidance, Lancaster Tree Manual shall preside.

1.3. Proper Identification: All trees shall be true to name as ordered and shall be labeled individually or in groups by species and cultivar (as appropriate).

1.3.1. Tree Specifications: All newly planted street tree stock shall have a 2.5 inch diameter as measured 4 inches above the root crown and a balled and burlapped root ball.

1.3.2. Proper mulching will be laid down for each tree planted, in accordance with the Lancaster Tree Manual guidance.

1.3.3. Each tree shall have a watering bag installed in accordance with the

Lancaster Tree Manual guidance.

1.4. Compliance: All trees shall comply with federal and state laws and regulations requiring inspection for plant disease, pests, and weeds. Inspection certificates required by law shall accompany each shipment of plants. Clearance from the local county agricultural commissioner, if required, shall be obtained before planting trees originating outside the county in which they are to be planted. Even though trees may conform to county, state, and federal laws, the City may impose additional requirements.

1.5. Inspection: The City reserves the right to reject trees that do not meet specifications as set forth in these guidelines or as adopted by the City. If a particular defect or substandard element can be corrected easily, appropriate remedies shall be applied. If destructive inspection of a root ball is to be done, the

City and Contractor should have a prior agreement as to the time and place of inspection, number of trees to be inspected, and financial responsibility for the inspected trees.

1.5.1. It is the Contractor’s responsibility to contact the City Representative to provide an opportunity for inspection of trees prior to delivery (optional) and at time of delivery (required).

1.5.2. The City shall be provided notice no less than 72 hours prior to delivery. The

City shall stipulate any special considerations to the Nursery prior to shipment.

1.6. Special Warranty: Installer agrees to repair or replace plantings and accessories that fail in materials, workmanship, or growth within specified warranty period.

1.6.1. Failures include, but are not limited to, the following:

1.6.1.1. Death and unsatisfactory growth, except for defects resulting from abuse, lack of adequate maintenance, or neglect by Owner, or incidents that are beyond Contractor's control.

1.6.1.2. Structural failures including plantings falling or blowing over.

1.6.2. Trees: A period of one (1) year or one (1) full growing season after the date of planting, whichever is greater.

1.6.3. Include the following remedial actions as a minimum:

1.6.3.1. Immediately remove dead plants and replace unless required to plant in the succeeding planting season.

1.6.3.2. Replace plants that are more than 25 percent dead or in an unhealthy condition at end of warranty period.

1.6.3.3. A limit of one replacement of each plant will be required except for losses or replacements due to failure to comply with requirements.

1.6.3.4. Provide extended warranty for period equal to original warranty period, for replaced plant material.

1.7. Maintenance Service: Provide maintenance by skilled employees of Landscape Installer. Maintain as required in Part 3. Begin maintenance immediately after plants are installed and continue until plantings are acceptably healthy and well established but for not less than maintenance period below.

1.7.1. Maintenance Period for Trees: A period of one (1) year or one (1) full growing season after the date of plating, whichever is greater.

1.7.2. Continuing Maintenance Proposal: From Installer to Owner, in the form of a standard yearly (or other period) maintenance agreement, starting on date initial maintenance service is concluded. State services, obligations, conditions, and terms for agreement period and for future renewal options.

PART 2 – MATERIALS

2.1. HEALTH AND STRUCTURE SPECIFICATIONS

2.1.1. These specifications apply to deciduous, broadleaf evergreen, and coniferous species. They do not apply to palms. Note that leaf characteristics will not be evident on deciduous trees during the dormant season.

2.1.2. Structure

2.1.2.1. Crown: The form and density of the crown shall be typical for a young specimen of the species or cultivar. The leader shall be intact to the very top of the tree.

2.1.2.2. Leaves: The size, color, and appearance of leaves shall be typical for the time of year and stage of growth of the species or cultivar. Trees shall not show signs of moisture stress as indicated by wilted, shriveled, or dead leaves.

2.1.2.3. Branches: Shoot growth (length and diameter) throughout the crown shall be appropriate for the age and size of the species or cultivar. Trees shall not have dead, diseased, broken, distorted, or otherwise injured branches.

2.1.2.4. Trunk: The tree trunk shall be relatively straight, vertical, and free of wounds (except properly made pruning cuts), sunburned areas, conks

(fungal fruiting bodies), wood cracks, bleeding areas, signs of boring insects, cankers, girdling ties, or lesions (mechanical injury). The terminal

Commented [DM1]: formatting bud on the leader shall be intact to the very top of the tree, and it shall be the highest point on the tree.

2.1.2.5. Roots: The root system shall be substantially free of injury from biotic

(e.g., insects and pathogens) and abiotic (e.g., herbicide toxicity and salt injury) agents. Root distribution shall be uniform throughout the container substrate, and shall be appropriate for the species or cultivar. At time of inspection and delivery, the root ball shall be moist throughout. Roots shall not show signs of excess soil moisture conditions as indicated by stunted, discolored, distorted, or dead roots.

2.1.3. Shade trees that grow to be large shall have one relatively straight central leader (Figure 1). Heading the tree is acceptable provided the central leader is reestablished in the nursery.

2.1.4. Main branches (Figure 2) shall be well distributed along the central leader, not clustered together. They shall form a balanced crown appropriate for the cultivar or species.

2.1.5. The diameter of branches (Figure 3) that grow from the central leader, or trunk, shall be no larger than two‐thirds (one‐half is preferred) the diameter of the trunk measured just above the branch.

2.1.6. The largest branches shall be free of bark inclusions that extend into the branch union (Figure 4 A and B).

A

B

Figure 1. Desirable Desirable Not desirable

Figure 2. Desirable Not desirable

Figure 3. Desirable Not desirable

Figure 4. Desirable Not desirable

2.1.7. Small‐diameter branches (Figure 5, left), particularly on trees less than 1 inch caliper, should be present along the lower trunk below the lowest main branch. These branches shall be no larger than 3/8 inch in diameter.

2.1.8. The trunk shall be free of wounds, sunburned areas, conks (fungal fruiting bodies), wood cracks, bleeding areas, signs of boring insects, cankers, or lesions. Properly made recent or closed pruning cuts are acceptable.

2.1.9. The trunk caliper (diameter) and taper (Figure 6) shall be sufficient so that the tree remains vertical without a stake.

2.1.10. The root collar (the uppermost roots; Figure 7) shall be within the upper 2 inches of the soil media (substrate). The root collar and the inside portion of the root ball shall be free of defects, including circling, kinked, and stem‐ girdling roots. Roots at the surface should grow mostly straight to the side of the container. You may need to remove soil near the root collar to inspect for root defects.

2.1.11. The tree shall be well rooted in the soil media. Roots shall be uniformly distributed throughout the container, meaning that roots should not be

Figure 5. Desirable Not desirable

Figure 6. Desirable Not desirable

Figure 7. Desirable Not desirable concentrated at the bottom of the root ball. Some roots should contact the container wall in the top half of the root ball (Figure 7, left). When the container is removed, the root ball shall remain intact. When the trunk is lifted, both the trunk and root system shall move as one. The imprint of the liner or smaller container shall not be visible (Figure 7, left).

2.1.12. The root ball shall be moist throughout at the time of inspection and delivery.

The roots shall show no signs of excess soil moisture as indicated by poor root growth, root discoloration, distortion, death, or foul odor. The crown shall show no signs of moisture stress as indicated by wilted, shriveled, or dead leaves or branch dieback.

PART 3 - EXECUTION

3.1 TREE PLANTING

3.1.1. Selecting quality trees: Planting quality trees begins by selecting the right tree for the right location and choosing vigorous, structurally sound trees from the nursery.

3.1.2. Digging the hole: A firm, flat‐bottomed hole will prevent trees from sinking.

Dig the hole only deep enough to position the root collar even with the landscape soil surface (Figure 8). Use a rototiller or shovel to loosen soil in an area three times the size of the root ball. This loose soil promotes rapid root growth and quick establishment.

3.1.3. Installing the tree: Remove soil and roots from the top of the root ball to expose the root collar; cut away any roots that grow over the collar (Figure 9).

Also cut any roots that circle or mat along the sides and bottom of the root ball

(Figure 10). The root collar shall be even with the landscape soil after planting

(see Figure 9). Backfill with soil removed from the hole. Minimize air pockets by packing gently and applying water. Build a berm 4 inches tall around the rootball to help force water through the root ball. Enlarge the berm as the tree establishes.

Figure 8. Loosening soil in a large area around the root ball allows for rapid root growth and quick establishment.

3.1.4. Mulching: A layer of organic mulch, such as leaf litter, shredded bark, or wood chips, helps protect tree roots from temperature extremes and conserves soil moisture. Mulch also helps prevent grass from competing with the tree for water and nutrients. The mulched area makes it easier to operate mowers and weed eaters without hitting the trunk and compacting soil. Apply mulch to a depth of 3 to 4 inches (slightly thinner on top of the root ball) (Figure

11).

3.1.5. Staking: Staking is used to hold trees erect, allow the root ball to anchor, and protect the trunk from damage by equipment. Stakes should be removed when the tree can stand on its own and the root ball is anchored. Stakes should be positioned away from the tree and secured to the trunk at the point where the tree stands straight. Do not use wire or any strap that will girdle the tree or damage the bark. Avoid using square wood secondary stakes.

3.2. TREE TRAINING AT PLANTING AND IN THE EARLY YEARS

A

B

A B

Figure 9. Remove soil and roots growing over the root collar (A) and place collar level with soil surface (B).

Figure 10. Cut roots at (A) to form new roots that grow away from the trunk.

Do not cut roots at (B), since the root defects will regrow.

Figure 11. Mulch shall taper to a slightly thinner layer on top of the rootball.

Figure 12. Double staked.

3.2.1. Trees that grow to be large are more structurally sound and cost‐effective to maintain when trained with a central dominant leader that extends 30 feet or more into the crown (Figure 13, left). Vigorous, upright branches and stems that compete with the central leader can become weakly attached (Figure 13, right).

3.2.2. Trees with branches spaced along the central leader, or trunk (Figure 13, left) are stronger than trees with branches clustered together (Figure 13, right).

Prune trees at planting to one central leader by removing or shortening

(shown) competing stems (Figure 14). All branches and stems shall be considerably shorter than the central leader after pruning is completed (Figure

14, right).

3.2.3. Remove or shorten branches that are larger than half the trunk diameter at planting and every few years thereafter. Shorten them by cutting back to a live lateral branch (Figure 17, right). This lateral branch shall be pointed away from the trunk and it should not be growing upright. The central leader shall be more visible in the crown center after pruning. Only large‐ diameter branches need to be pruned because they compete with the leader and could be weakly

Figure 13. Good tree structure (left); poor structure (right).

Figure 14. Shorten competing stems to improve structure.

Figure 15. Only large branches need pruning (L). Small branches (S) do not need to be pruned.

Retain this lateral branch.

L

S S attached (Figure 17, L). Small branches (Figure 17, S) do not need pruning because they will not compete with the leader.

3.2.4. Shorten or remove the largest low branches when the tree is young to keep them small (Figure 16). This ensures that only a small wound is created when they are eventually removed from the trunk.

3.2.5. The best way to shorten large or long stems and branches is to cut them back to a live lateral branch (Figure 17). This slows growth on the pruned parts and encourages growth in the dominant leader creating sound structure.

3.2.6. Remove larger branches by making three cuts. This prevents the bark from peeling or splitting off the trunk below the cut. Make the final cut back to the branch collar (enlarged area around union of branch where it joins the trunk).

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Figure 16. Shortening larger low branches concentrates growth in the leader and improves tree structure.

After

Live lateral branch.

Before

Figure 17. Reduce a stem back to a live lateral branch to slow its growth.

3.2.7. Structural Pruning Checklist

a) Develop and maintain a central leader.

b) Identify the lowest branch in what will become the permanent crown.

c) Prevent branches below the permanent crown from growing larger than half the trunk diameter.

d) Space main branches along the central leader.

e) Reduce vigorous upright stems back to lateral branches or remove entirely (Figure 20).

f) Reduction cuts can be used on trees at planting to subordinate branches that are codominant (Figure 18). Some upright stems and branches can be removed entirely back to the trunk. Heading cuts may have to be used occasionally.

3.3. IRRIGATION & MULCHING

3.3.1. Immediately following planting, all newly planted trees shall be deeply irrigated by applying at least twenty-five (25) gallons of water, and shall be continued weekly during hot and/or dry periods of the first planting season using TreeGators or other deep irrigation methods.

3.3.2. All tree plantings shall be mulched with two to three inches of composted wood chips, or aged, coarse fibrous bark. Mulch shall be placed in a circle a minimum of two to three feet in diameter, but not touching a tree trunk. Mulch and debris shall be removed from all pedestrian surfaces (e.g., sidewalks).

END OF SECTION 02930

Figure 18. Before and after pruning at planting for structure.

Commented [DM2]: do we want a page break here?