Influence of pre-transplanting treatments on root establishment in woody plants

Irena Neffeova

The overall goal of research on woody landscape plant roots at WSU is to determine the best 88 management practices when transplanting woody plants for proper root establishment and long- 89 term survival. Many landscape trees die before they should, because of poor root system 90 establishment, or often snapping off at the base of the trunk in a windstorm due to poor root 91 architecture. A root system should have a strong connection to the trunk (flare) and a root plate 92 with long straight roots and radial root distribution to serve as an anchor and function as a 93 support system. Nursery-grown trees typically have roots with kinks and circles in them, 94 especially if they are produced in containers. Research has shown that cutting through these 95 circling roots or removing any problematic roots at transplanting may reduce the problem, but 96 many questions on the effectiveness of such interventions remain. This study looked at early root 97 development in young woody plants without circling root problems, because they had little 98 secondary growth present yet in the roots. We applied three pre-transplanting treatments: pop & 99 drop (control), wash and spread (bare-rooting), and cut through the middle of the root ball using 100 Pinus sylvestris (Scotch pine) and Pinus contorta var. latifolia (Lodgepole pine). In conclusion, part of this study showed that woody plants should have their root systems disturbed. In this pre- 102 transplanting treatment study, young woody plants (seedlings) were found positively to respond 103 to the disruptive treatments. Bare-root trees were shown to have fewer root defects, but they 104 were not better than to control in other variables. This experiment showed that trees in the cut 105 treatment had the most straight lateral roots. Trees in all treatments had similar lateral root 106 distribution. However, because all treatments also had some problematic roots, such as the bare- 107 root treatment did not have the lateral roots straight as we expected, we cannot clearly conclude 108 what treatment is best to do before transplanting. Knowing that previous research has shown that 109 disrupting treatments are better for the tree’s survival than pop-and-drop method and either form 110 of disruption was better than the control, the disrupting treatments are better choices than the 111 pop-and-drop. Finally, we propose that more research should be conducted on root disruption 112 methods for tree seedlings.

Influence of pre-transplanting treatments on root establishment in woody plants

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