Post-Transplant Root System Expansion in Juniperus chinensis L. as Influenced by Production System Mechanical Root Disruption and Soil Type

Abstract

Juniperus chinensis (L.) ‘Sea Green’ from 3.8 1 (#.1) containers (CG) and comparably sized field grown plants balled and burlapped (B&B) were planted in clay and loam soil in mid-June. Prior to transplanting, root balls of the CG plants were either mechanlcally disrupted by vertical cuts (D/CG) or left undisturbed (CG). Root growth beyond the original root ball and shoot extension growth in loam soil were determined at 8 and 12 weeks, while similar data were collected from loam and clay soils at 16 wks. B&B plants and D/CG plants produced greater dry weight of new roots, but less shoot growth at 8 wks than CG plants with an undisturbed root ball. By 16 wks, B&B plants had produced greater new root dry weight than either CG treatment and shoot growth was not different among treatments. In clay soil B&B plants produced greater dry weight of new roots than CG plants. Root ball disruption reduced new root growth in the heavy soil compared to CG plants. Shoot growth was not different among treatments in the heavy soil, but was significantly diminished compared to shoot growth on the lighter, loam soil.

A review of nursery production systems and their influence on urban tree survival

“…Without more long-term survival studies and side-by-side comparisons of production practices, findings seem to indicate that varying production systems offer species-specific effects relative to tree establishment and survivability. Blessing and Dana, 1987;5 Buckstrup and Bassuk, 2000;6 Gilman, 2001;7 Gilman et al, 2010a;  Greater protection against mechanical injury during production and transport 15  Lower planting cost than B&B 9  Retention of fine root biomass 4  Container designs and improvements reduce circling root growth, increase fine root biomass, and improve survivability 1,2,3,7,8,14,19,21…”

“…square; pyramidal) containers, and features such as drainage holes, and ribbed or stepped plastic, to minimize circling root growth (Appleton, 1989(Appleton, , 1993. Container-grown nursery stock retains 100% of the root system at the time of planting, in comparison to B&B plants, which may be transplanted with as little as 5% of the original root system (Blessing and Dana, 1987). However, this estimate does not reflect concerns associated with root deformation and necessary pre-transplant pruning, nor does this ensure higher post-transplant survival rates.…”

“…Trees grown in a production field can be harvested BR or B&B. The B&B root ball excavation process can leave as much as 95% of the tree"s total root system in the field, with up to 30% of what is left in the field estimated to be fine root mass (Blessing and Dana, 1987;Mathers et al, 2007). This can be detrimental due to the loss of fine root biomass, which is critical for water and nutrient acquisition (Yin et al, 2014).…”

Urban Highway Roadside Soils and Shrub Plantings Enhanced by Surface-Applied and Incorporated Organic Amendments

“…Although it is commonly recommended that the circling roots of container-grown trees and shrubs be cut or shaved before planting to prevent stemgirdling roots from developing (Ophardt and Hummel 2011;Watson et al 2014b), root systems of the container-grown shrubs in this study were left intact at transplant. At the end of one growing season, Blessing and Dana (1987) found that vertically cutting the root systems of 3.8 L container-grown Chinese juniper at transplant reduced new root growth in a heavy silty clay soil compared to undisturbed root systems. In the current study, roots were observed growing throughout the amended zones in the surface-applied and incorporated treatments, but were growing only in the original planting hole and the bark mulch layer of the con-trol treatment.…”

The Management of Tree Root Systems in Urban and Suburban Settings II: A Review of Strategies to Mitigate Human Impacts

“…Circling roots on the surface of the container root ball are widely recognized as a defect and it is common practice to disrupt these by making several vertical cuts, or "slashes, " on the outside of the root ball before planting (Ellyard 1984;Blessing and Dana 1987;Arnold 1996;. Methods that disrupt circling roots do not eliminate descending, ascending, and kinked roots.…”