Upper Snowy Landcare Network has just completed a trial of Hiko (small) vs.
Forestry (large) tubestock under their Dieback Project to plant back trees and
shrubs. Under a $50,000 grant from the National Landcare Program, three
different sites across the Monaro were planted with 1000 trees and shrubs each in 20:80 mix of Forestry and Hiko tubestock. They were monitored for survival and growth rate over the ensuing 6 months. Survival rate at 6 months was at a record high at 88.8%. This is most likely due to watering several times during the driest periods post-planting. At 6 months post-planting there were significant survival and growth advantages of using larger tubestock in one of the three sites (Fig. 1).
These results are similar to those from another two sites planted previously by Upper Snowy Landcare Network. However, in that case, the survival advantage was only detectable in plants given Seasol at the time of planting, and the growth advantage was only visible in plants not given Seasol (Fig. 2).
Overall, it seems there may be advantages to using larger tubestock, especially in situations where nutrients and water are not limiting. However, given the higher cost per plant of Forestry tubestock, and the potential for J-rooting in Forestry tubes that can kill the trees later in life, Upper Snowy Landcare Network will continue to use a mixture of Forestry and Hiko tubes in their plantings until the evidence becomes clearer.
For more information, contact us.