Structural defects most frequently associated with failure. Percentage is of the total number of failures for each tree group.
| Top three | Q. agrifolia | Hardwoods | Eucalyptus | Conifers | Q. lobata | Other oaks |
|---|---|---|---|---|---|---|
| 1 | Failed portion dead (root) 11.2% | Heavy lateral limbs (branch) 9.2% | Heavy lateral limbs (branch) 18.5% | Heavy lateral limbs (branch) 36.5% | Heavy lateral limbs (branch) 9.6% | Heavy lateral limbs (branch) 17.7% |
| 2 | Multiple trunks/ codominant stems (trunk) 8.6% | Multiple trunks/ codominant stems (trunk) 8.7% | None (branch) 9.8% | Multiple trunks/codominant stems (trunk) 6.3% | Failed portion dead (root) 8.2% | Failed portion dead (trunk) 11.4% |
| 3 | Failed portion dead (trunk) 7.8% | Failed portion dead (trunk) 6.5% | Multiple branches one point (branch) 8.7% | Multiple trunks/ codominant stems (branch) 6.3% | Heavy lateral limb (trunk) 5.5% | None (root) 8.9% |