28 Gilman et al.: Retention Time in Nursery Containers and Root Pruning at Planting by container walls. However, few trees destined for landscapes are grown in this substrate (per- sonal observation). Coutts et al. (1990) found that under certain conditions some taxa are stabilized aſter planting by straight adventitious roots that develop following out-planting from propaga- tion containers. Straight lateral roots radiating from the trunk are associated with well-anchored trees (Lindgren and Örlander 1978; Lindström and Rune 1999; Ortega et al. 2006). In addition to modified (i.e., not solid) container wall design, root pruning during container production (Harris et al. 1971; Gilman et al. 2010) and at landscape planting (Gilman and Wiese 2012) has been asso- ciated with an abundance of straight roots growing into the backfill soil and into the landscape soil, and it can be used to improve root architecture. The objective of this study was to determine the impact of retention time in 11, 57, and 170 L nursery containers, given 32 months total production time in the nursery, and of root pruning at landscape plant- ing on establishment and anchorage during four subsequent growing seasons. The taxa chosen for study were selected due to their popularity in many parts of temperate North America and elsewhere. MATERIALS AND METHODS Growing and Planting Trees In February 2007, 80 uniform rooted cutting liners of Magnolia grandiflora L. Miss Chloe® rooted in square propagation containers (7.3 cm across × 14 cm deep smooth-sided, solid-walled, Ander- son Band AB39, Stuewe and Son, Inc., Tangent, Oregon, U.S.), and Acer rubrum L. ‘Florida Flame’ and Ulmus parvifolia Jacq. Allée® rooted in circu- lar propagation containers (5.1 cm top diameter, 13 cm tall ribbed, solid-walled, 38 Groovetube, Growing Systems, Inc., Milwaukee, Wisconsin, U.S.) were shiſted into 11 L round, black, solid- walled nursery containers (27 cm top diameter, 25 cm tall; Nursery Supplies, Inc., Chambersburg, Pennsylvania, U.S.). Magnolia roots originated pri- marily near the end of the stem cutting, whereas roots on Acer and Ulmus emerged near the end and from along the buried stem. The point where the top-most root emerged from the stem cutting was placed approximately 13 mm below the 11 L sub- strate surface by removing an appropriate amount ©2017 International Society of Arboriculture of substrate and deflected roots from the top of liner root ball. The containers were placed on wo- ven black ground cloth in USDA Hardiness Zone 8b (mean low temperature -10°C) in Gainesville, Florida, U.S. Low winter temperatures in January 2008 killed numerous Ulmus resulting in 48 of the 80 trees leafing out in spring; no Acer or Mag- nolia were damaged by low winter temperatures. All trees were grown in three progressively larger containers (11, 57, and 170 L) for a total of 32 months with varying retention times in each con- tainer. Twenty Magnolia and Acer, and twelve Ulmus in 11 L containers were randomly assigned to each of the following four retention-time treatment com- binations: 1) shiſted June 2007 into 57 L solid-walled containers (black plastic round, 44 cm top diameter × 35 cm tall, Nursery Supplies Inc., Chambersburg, Pennsylvania, U.S.) aſter four months in 11 L and then shiſted February 2008 into solid-walled 170 L containers (75 cm top diameter × 47 cm tall) aſter eight months in 57 L; 2) shiſted September 2007 into 57 L aſter seven months in 11 L and then shiſted July 2008 into 170 L aſter 10 months in 57 L; 3) shiſted November 2007 into 57 L aſter nine months in 11 L, and then shiſted November 2008 into 170 L aſter 11 months in 57 L; and 4) shiſted February 2008 into 57 L aſter 12 months in 11 L and then shiſted April 2009 into 170 L aſter 14 months in 57 L. This resulted in 32 months in nursery containers for all trees (see Retention time in containers, Table 1). Root balls were not pruned when shiſting. All trees were retained in 170 L containers through October 2009, when five trees of each retention-time com- bination were harvested and root balls dissected for data collection (described in the compan- ion study, Gilman et al. 2015b). This leſt 15 Acer and Magnolia, and seven Ulmus per retention- time combination for planting into the landscape. On 3–6 May 2010, 10 trees randomly selected from the remaining 15 per retention-time com- bination for Acer and Magnolia were planted into landscape soil (Millhopper fine sand - loamy, sili- ceous, hyperthermic Grossarenic Paleudults) in a grid pattern (3.0 m × 3.7 m) so that the top of the root ball was even with the landscape soil. For Magnolia and Acer, root balls of five trees of each retention-time combination were leſt intact (not pruned); five trees were root pruned for total of 40 planted trees of each taxa. Root pruning was per-
January 2017
| Title Name |
Pages |
Delete |
Url |
| Empty |
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
