2013 ASHS Annual Conference

The most commonly used container type for nursery tree production is the black plastic (BP) container. The longer trees remain growing in BP, the greater the potential for the development of circling and malformed roots. Root injury sustained during production may negatively affect tree health when planted in the landscape. Research at Colorado State University used Pyrus calleryana Decene. ‘Glen’s Form’ (Chanticleer®) to compare tree production using two non-conventional, fabric container types, Root Pouch® (RP), and Smart Pot® (SP), with BP containers to determine the effects of container type on tree roots following transplant in the landscape. After growing in a nursery production setting, trees were planted into bluegrass turf in Fall 2010 and Spring 2012. Post-transplant success of trees was determined during the growing season using pre-dawn leaf water potential and infrared leaf canopy temperature to detect stress. Trees were harvested in Fall 2011 and 2012 using an air spade (after one and two growing seasons) to evaluate transplant establishment using growth measurements (e.g. root and shoot re-growth, leaf area, height, caliper, and branching).   In 2011 and 2012, there were no significant container effects on height, caliper, root:shoot ratio, and dry leaf, shoot, and root weight. In addition, there were no container effects on pre-dawn leaf water potential and infrared canopy temperature. In 2012 there were significant container effects for average root re-growth beyond the original root ball: BP had 17.5% root re-growth compared to 30.2% and 29.4% for RP and SP, respectively.  There were no significant differences for root re-growth in 2011 (8.4% BP, 10.6% RP, and 10.2% SP). Though there were no significant differences in 2012 for above-ground growth, nor dry root weight, root re-growth and visual root architecture differed among the three container types. One preliminary conclusion from this study is that you cannot predict below-ground establishment potential based on above-ground growth. Another conclusion is that using best management practices when planting is unlikely to correct problems caused by container type in the nursery.