Table 2.

Effect of root pruning root balls from 170 L containers at landscape planting in September 2008 on landscape growth and anchorage.

Root pruningzTrunk diameter increase 2011y (mm)Trunk diameter increase 2012y (mm)Percent trunk with tangent/circling roots (>10 mm diameter) touching trunkxRoot ball imprint ratingw (1–5)Rest anglev (degrees)
None45 au57 a5 b3.6 a0.9 b
Shaved41 b54 b15 a1.2 b1.0 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.