Two rootball sizes as well as a nontransplanted control were randomly assigned to Acer saccharum Marsh. (sugar maple) trees in four adjacent nursery rows at Waynesboro Nurseries in Waynesboro, Va. One size (75 cm in diameter) corresponded to the American Association of Nurserymen standards. The other rootball size was 90 cm in diameter. Trees were transplanted just before bud swell or during shoot elongation. Rootball size had no effect on height, stem diameter, or twig growth, total nonstructual leaf nitrogen content (LNC), or total stem nonstructual carbohydrate (TNC). Height growth was reduced by 81%, stem diameter growth by 71%, and twig growth by 82% for trees transplanted before bud swell compared to nontransplanted trees. LNC was 25% more on transplanted trees than on nontransplanted trees, presumably due to a dilution effect. TNC was 20% higher on transplanted compared to nontransplanted trees. Growth was severely curtailed on late-transplanted trees for all characteristics measured compared to all other treatments.
J. Roger Harris, Patricia Knight and Jody Fanelli
J. Roger Harris, Patricia Knight and Jody Fanelli
The effect of fall vs. spring transplanting was tested on landscape-sized Chionanthus virginicus L. at a research farm in Blacksburg, Va. Two fall transplanting dates (11 Nov. and 1 Dec. 1994) were selected so that soil temperatures were decreasing and near 10 °C for the earlier fall date (11 Nov.) and decreasing and near 5 °C for the later fall transplanting date (1 Dec.). The spring date (14 Mar. 1995) was selected so that soil temperatures were increasing and near 5 °C. All trees were transplanted with rootballs of native soil wrapped in burlap (B&B). Fringe tree was clearly tolerant of fall transplanting. Trees transplanted on 11 Nov. had a larger leaf area 1 month after bud set the next summer and had wider canopies and more dry mass of new roots at leaf drop than trees transplanted on the other dates. Trees transplanted on 14 Mar. had less total leaf area, leaf dry mass, and lower maximum root extension into the backfill soil than trees transplanted on 11 Nov. or 1 Dec. No root growth occurred beyond the original rootball until about early July (1 month after bud set) in any treatment, suggesting that first season posttransplant irrigation regimes need to focus on rootballs, not surrounding soil areas.
J. Roger Harris, Richard Smith and Jody Fanelli
Rapid posttransplant root growth is often a determining component of successful establishment. This study tested the effect of transplant timing on first-season root growth dynamics of bare-root Turkish hazelnut trees. Trees were either harvested and planted in the fall (F-F), harvested in the fall and planted in the spring after holding in refrigerated storage (F-S), or harvested and planted in the spring (S-S). All trees were transplanted into 51-L containers, adapted with root observation windows. Root growth began in F-F and F-S trees 1-2 weeks before spring budbreak, but was delayed in S-S trees until ≈3 weeks after budbreak. Budbreak was 6 days earlier for fall-harvested than for spring-harvested trees. No new roots were observed before spring. Root length accumulation against observation windows (RL) was delayed for S-S trees, but rate of increase was similar to F-F and F-S trees soon after growth began. Seasonal height, trunk diameter growth, and RL were similar among treatments. Surface area of two-dimensional pictures of entire rootballs was not correlated with seasonal RL.
J. Roger Harris, Jody Fanelli and Paul Thrift
Description of early post-transplant root growth will help formulate best transplanting strategies for landscape trees. In this experiment, the dynamics of early root system regeneration of sugar maple (Acer saccharum Marsh. `Green Mountain') and northern red oak (Quercus rubra L.) were determined. Field-grown 4-year-old trees were transplanted bare-root into outdoor root observation containers (rhizotrons) in Oct. 1997, Nov. 1997, or Mar. 1998. All trees were grown in the rhizotrons until Oct. 1998 and then transplanted, with minimally disturbed rootballs, to field soil and grown for an additional two years. October-transplanted trees of both species began root regeneration earlier and regenerated more roots, as judged by accumulated root length on rhizotron windows, than Nov.- or March-transplanted trees. Median date for beginning root extension for sugar maples was 48, 22, and 0 days before budbreak for October-, November-, and Marchtransplanted trees, respectively. Median date for beginning root extension for northern red oak was 4, 21, and 14 days after budbreak for October-, November-, and Marchtransplanted trees, respectively. Height and trunk diameter growth were similar for all treatments within each species for 3 years after application of treatments. Early fall transplanting will result in earlier first season post-transplant root growth for sugar maple and northern red oak. Earlier post-transplant root growth will likely increase resistance to stress imposed by harsh landscape environments.
Matt Kelting, J. Roger Harris, Jody Fanelli and Bonnie Appleton
Application of biostimulants, humate-based products marketed as aids to plant establishment, may increase early post-transplant root growth and water uptake of landscape trees. We tested three distinct types of biostimulants on root growth and sapflow of balled and burlapped red maple (Acer rubrum L. `Franksred') trees. Treatments included: humate, 1) as a wettable powder formulation, applied as a soil drench; 2) as a liquid formulation to which various purported root growth—promoting additives had been added, also applied as a soil drench; 3) as a dry granular formulation, applied as a topdress; and 4) a nontreated control. Root growth was monitored through single-tree rhizotrons, and sap flow was measured with a heat balance sapflow system. Roots were first observed in the rhizotron windows 38 days after planting. No biostimulant-treated trees had more root length than nontreated controls, and the two soil drench treatments had the lowest root length throughout the 20 weeks of post-transplant observation. All biostimulants increased sapflow.
J. Roger Harris, Alex Niemiera, Jody Fanelli and Robert Wright
Two experiments tested the effects of root pruning on growth during first-season production of pin oak (Quercus palustris Muenchh.). Experiment one tested the effect of root pruning developing radicles at 5, 10, or 15 cm (2, 4, or 6 inches) below the substrate surface. After 11 weeks, total root length was not affected by root pruning, but root-pruned seedlings had more main lateral [>2-mm (0.08-inch) diameter] roots than those that were not root pruned. Shallow pruning increased the number of main lateral roots. Experiment two tested the effect of initially producing plants in different-depth bottomless containers [5, 10, 15, or 20-cm (2, 4, 6, or 8-inch) depth] on growth after transplanting to #2 [6 L (1.6 gal)] containers. Shoot and root growth in #2 containers were lowest when plants were originally produced in 5-cm-deep containers. Plants with the greatest height and highest root:shoot ratios were obtained when plants were grown initially in 10-cm-deep containers. Predicted optimum depth of bottomless containers from regression equations ranged from 11.3 cm (4.5 inches) to 14.2 cm (5.5 inches) for the different growth parameters measured. The importance of these findings are: Pruning developing radicles of pin oak seedlings increases the number of main lateral roots but not overall root length. Growers can maximize growth in #2 containers by initially growing in 10-cm-deep bottomless containers before transplanting to #2 containers.
Lisa E. Richardson-Calfee, J. Roger Harris and Jody K. Fanelli
Fundamental information regarding posttransplant root and shoot growth dynamics is needed to better understand transplant establishment. Seasonal patterns of root, shoot, and trunk growth of balled-and-burlapped and pot-in-pot (PIP) sugar maples (Acer saccharum Marsh.) transplanted at leaf drop (Nov. 2000), late fall (Dec. 2000), early spring (Mar. 2001), budbreak (Apr. 2001), or budset (July 2001) were measured and compared with nontransplanted field- and PIP-grown trees. All trees exhibited a pattern of maximum shoot extension, root growth, and trunk expansion in early May, late May, and early June, respectively. Maximum root growth was concurrent with early trunk expansion, both of which began when shoot growth was decreasing. Root growth was characterized by periods of abundant growth in late May and early June and less growth in summer and early fall. Transplanting at fall leaf drop, in late fall or spring, or at budbreak did not appear to radically disrupt the normal growth periodicity of sugar maple. However, transplanting at budset (summer) resulted in abundant root growth 11 weeks later than the period of maximum root growth in all other treatments. Our data indicate that similar amounts of root regeneration can be expected for irrigated July-transplanted trees as for trees transplanted in fall and spring. As well, our study provides evidence of root mortality during the winter and spring after the first posttransplant growing season. Although minimal root mortality was evident in nontransplanted field trees, substantial root mortality was evident in the nontransplanted PIP trees during winter and early spring.
J. Roger Harris, Jody Fanelli, Alex Niemiera and Robert Wright
Two experiments were conducted to test the effects of early root pruning on growth of pin oak (Quercus palustris Muenchh.). Experiment one tested the effect of radicle tip removal when radicles had reached 5, 10, or 15 cm below the substrate surface. Total root length was not affected by treatment, but root-pruned trees had more large-diameter lateral (primary lateral) roots than trees that were not root-pruned. The number of primary laterals increased if the radicle tip was removed at more shallow depths. Experiment two tested the effect of liner production in bottomless containers (roots air-pruned) of 5-, 10-, 15-, and 20-cm depths on subsequent growth in #2 (6-L) containers. Top and root growth was generally lowest in 5-cm-deep containers and highest in 10- or 15-cm-deep containers.
Patricia R. Knight, James R. Harris and Jody Fanelli
Bareroot Corylus colurna were grown in 7.5-liter containers from 11 Apr. until 27 June 1994. The growing medium was fritted clay. Fertility levels included no fertilization, 100 ppm N, or 200 ppm N. Plants were root pruned to remove none or one-quarter to one-half of the primary roots. Root pruning at any level resulted in decreased height, shoot, and root dry weights and number and length of new shoots. One-quarter primary root removal resulted in lower root: shoot ratios compared to plants that were unpruned. One-half primary root removal further reduced root: shoot ratios. One-half primary root removal also reduced total leaf area compared to unpruned controls. Fertilization at 200 ppm N increased leaf numbers and total leaf areas compared to plants receiving no fertilization.
Lisa Richardson-Calfee, J. Roger Harris* and Jody Fanelli
Seasonal effects on transplant establishment of balled-and-burlapped (B&B) shade trees are not well documented. Early post-transplant root growth and above-ground growth over 3 years were therefore documented for November- and March-transplanted northern red oak (Quercus rubra L.) and willow oak (Q. phellos L.). Survival of red oak was 100% for both treatments. Survival of November- and March-transplanted willow oak was 67% and 83%, respectively. No new root growth was observed outside or within the root balls of either species upon excavation in January. However, new root growth was evident when subsamples were excavated the following April for November-transplanted trees of both species, indicating that root system regeneration of November-transplanted trees occurs in late winter and/or early spring, not late fall and/or early winter. November-transplanted red oak, but not willow oak, had grown more roots by spring bud break than March-transplanted trees. While height growth of willow oak was nearly identical between treatments after 3 years, November-transplants exhibited greater trunk diameter increase for all 3 years. Overall, season of transplant had little effect on height and trunk diameter increase of red oak, even though November-transplanted trees grew more roots prior to the first bud break following transplant. Among the willow oaks that survived, season of transplanting had little effect on height growth, but November transplanting resulted in greater trunk diameter increase. However, considering the mortality rate of November-transplanted willow oak, March may be a better time to transplant willow oak in climates similar to southwest Virginia.