162 Gilman et al.: Nursery Root Pruning and Tree Orientation at Planting on Growth and Anchorage the root ball was placed in the planting hole a 15 cm wide volume of undisturbed soil at the edge of hole was pushed into the hole. The rest of the void around the root ball was filled with soil from the planting hole. Water was added to settle backfill soil and soil was lightly tamped by foot to stan- dardize compaction of backfill soil. No berm or water ring was constructed around the root ball. Chipped, whole branches and leaves from utility June 2011 and 2012. Weeds were controlled in the mulch with periodic (three to four) annual appli- cations of glyphosate (isopropylamine salt, 41%); vegetation between rows was periodically mowed. March and June 2009, and 400 g of 20-0-8 (N-P2O5 K2 O5 -K2 Evaluating Post-Planting Anchorage and Growth To evaluate lateral tree stability (anchorage), trunks were pulled laterally with a winch in late August/early September 2009, 2010, and 2011 for maples, and October 2009, 2010, and 2011 for oaks. All trees were pulled (one or two blocks each rain-free day) with a steel cable and elec- tric winch (Model 40764; Chicago Electric Power Tools, Inc., Camarillo, California, U.S.) in the 350 degree azimuth (from north) direction. There was no prevailing wind direction at the site. The winch attached to a cable about 1.2 m from the ground remained parallel to ground. A 3,629 kg capacity load cell (SSM-AF-8000; Interface Inc., Scottsdale, Arizona, U.S.) was placed in-line with the winching cable. An inclinometer (model N4; Rieker Inc., Aston, Pennsylvania, U.S.) was mounted to a fabricated steel plate (5.1 cm × 7.6 cm). The plate was secured to the trunk 15 cm from soil surface, which was just above the swol- len flare. The cable was winched at 2 cm•sec-1 until the inclinometer tilted five degrees from ver- tical start position; then the cable was released. Data from load cell and inclinometer were col- lected at 2 Hz by Data Acquisition System (National Instruments Corporation, Austin, Texas, U.S.). Data from pulling tests were displayed in real time on a ©2016 International Society of Arboriculture line clearance operations were applied as mulch 12 cm thick (before settling) 1.8 m wide within each of four rows. Trees were irrigated on the root ball three times a week and were fertilized under the crown with 200 g of 16-4-8 (N-P2 O) in - O) in March and May 2010, and March and laptop running LabView soſtware (v: 7.0; National Instruments, Austin, Texas, U.S.). Trunk bend- ing stress was calculated according to Equation 1: [1] 𝜎𝜎ᆉ৹䯧 = 𝐹𝐹ᆉ৹䯧 ∙ 𝑑𝑑ᆉ৹䯧 ∙ 𝑅𝑅ᆉ৹䯧 𝜋𝜋ᆉ৹䯧 4 ∙ 𝑅𝑅ᆉ৹䯧 4 where σ = bending stress F = pulling force d = distance from pulling point to inclinometer R = trunk radius (calculated as halving diameter measured with a diameter tape) Trunk diameters at 15 cm from ground and tree height were measured at planting and in Sep- tember of each year through 2013. In May 2014, soil was removed with high-speed air in a 40 cm radius around the trunk to expose the top 12 cm of the original 51 L root ball. Measurements included diameter of the five largest roots 10 cm beyond edge of the 51 L container in the top 12 cm of soil pro- file on the north and south 180 degree circumfer- ence of the tree (total 10 roots on each tree). Root diameter was measured from the top of the root to the bottom and perpendicular to that, and these were averaged to calculate the cross-sectional area (CSA) of a circle on the ten roots on each tree. Visual root system imprint (1 = little imprint with mostly straight roots; 5 = strong imprint, many roots deflected by and retaining the shape of the container) caused by roots deflected by the 12 L or 51 L container walls was rated for each tree. Experimental Design and Statistical Analysis Trees in 51 L containers were placed on nurs- ery ground cloth in a randomized complete block design described in Gilman et al. (2010b). Trees of both taxa were planted into landscape soil in a randomized complete block design with 2 taxa × 2 root prunings × 2 tree orientations × 5 blocks = 40 trees. Taxa were statistically analyzed separately. Main effects on trunk tilt from root pruning and tree orientation were analyzed in the GLM proce- dure of SAS (1992) with repeated measures two- way analysis of variance (ANOVA); main effects on root CSA from root pruning, tree orientation, and side of the trunk (north or south) were analyzed with three-way ANOVA. Means were separated
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