Sunday, May 22, 2011

Tree Problem 5: Tall Black Walnut

Site: W side of my yard (NE Portland)

+ Big tree providing much appreciated shade late in the day in the summer. Producer of "Squirrel TV" giving many hours of amusement for us and our dog.
- Shows signs of some pretty aggressive pruning. One falling branch could ruin our whole afternoon.

Tree Characteristics
A tall limbed up old Black Walnut (Julans nigra) a mature tree with a single trunk DBH 29". Live crown ratio is around 40%.

Tree Health
New foliage looks healthy. No significant signs of decay.

Site Conditions
Residential site, between two driveways and next to a low wooden fence, shrub border with no regular irrigation. No signs of recent site disturbance, no paving, fill, or grade work in the dripline, but the driveways and homes occupy probably 30% of the dripline. Slope is level. Between houses on the East and West.

Two houses, fence, landscape plants.

Tree Defects
Somewhat constrained root space. Signs of severe pruning and growth response from heading cuts. No clear dominant leader. Multiple attachments with large branches.

Hazard Rating
Part most likely to fail: branch failure. Moderate failure potential on large parts with significant targets for a hazard rating of 2+3+4 = 9.

Hazard Abatement
Corrective pruning, possibly requiring cabling (3/8" common) for additional support of week attachments. Rationale: This is a very valuable tree providing a lot of services. Focusing on establishing a sound leader and reducing the problems from the multiple attachments should reduce the risks. Attention should be paid to the growth direction of any significant branch. Annual inspection is recommended.

Other Recommendations
This is a phenomenal tree.

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