Growing Blackgum Whips in Ground Beds Increases Survival and Growth Following Transplanting to Field

Abstract

Abstract Difficult-to-transplant species can be produced in containers and transplanted with high survival. However, circling roots can develop even in containers designed to prevent root malformation, requiring root pruning before transplanting and this results in transplant shock. In order to determine the effect of different containers and substrates on whip growth and survival after transplanting, blackgum (Nyssa sylvatica Marsh.) whips were grown in four container types (Spinout®-treated plastic, tall or short fiber containers or in ground beds) and two substrates (pine bark: Com-Til™ and Haydite: Com-Til™). Container-grown whips were overwintered in unheated polyhouses; bed-grown were overwintered out-of-doors with no winter protection. Two year branched whips grown in Haydite: Com-Til™ were bare rooted and root pruned before transplanting. Whips grown in containers required root pruning to correct root malformation, while whips grown in pine bark: Com-Til™ in ground beds were root pruned as part of the harvesting process. Container and substrate treatment did not affect whip stem diameter, but whips grown in ground beds in pine bark: Com-Til™ were the tallest. Overwinter survival for container-grown whips ranged from 77 to 88% and averaged 85% for whips grown in ground beds. The percentage of whips reaching 1.2 m in height ranged from 53 to 97% for whips produced in tall fiber containers in Haydite: Com-Til™ substrate and in short fiber containers in Haydite: Com-Til™ substrate, respectively. Two years after whips were transplanted, survival averaged 98% (174 of 178). Two years after transplanting, whips produced in beds in pine bark: Com-Til™ substrate had the greatest caliper. Whips produced in ground beds in pine bark: Com-Til™ offer an acceptable alternative to container-produced blackgum whips; they had high overwintering and transplant survival; they were taller at the end of the two year whip production period, and two years after transplanting to field plots they had the largest trunk caliper.