Effect of root pruning root balls from 170 L containers at landscape planting in September 2008 on landscape growth and anchorage.
| Root pruningz | Trunk diameter increase 2011y (mm) | Trunk diameter increase 2012y (mm) | Percent trunk with tangent/circling roots (>10 mm diameter) touching trunkx | Root ball imprint ratingw (1–5) | Rest anglev (degrees) |
|---|---|---|---|---|---|
| None | 45 au | 57 a | 5 b | 3.6 a | 0.9 b |
| Shaved | 41 b | 54 b | 15 a | 1.2 b | 1.0 a |
↵z Root pruning removed (shaved) the outer 3 cm of the 170 L root ball periphery prior to planting into landscape soil.
↵y Not significant (P > 0.19) for the years 2009 and 2010; trees installed September 2008.
↵x Percent of trunk circumference with roots >10 mm diameter growing tangent to or circling trunk that touched or were embedded into trunk bark.
↵w Imprint on the root system from deflection from 170 L container, where 1 = no imprint and 5 = high imprint; rating visually estimated by two observers individually.
↵v Trunk angle after releasing winch from 5 degree trunk pull 40 months after planting.
↵u Numbers followed by a different letter within columns are statistically different at P < 0.05; n = 24, averaged across container planting depth and landscape planting depth due to insignificant interactions (P > 0.06 and > 0.19, respectively) with root pruning.