Herbicide screening pot trial for wildling conifer control (Pinus contorta, P. mugo and Pseudotsuga menziesii)

Authors: Stefan F. Gous, Michael S. Watt, Brian Richardson, Mark O. Kimberley
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 2010, Issue N.Z.J.For. 55(1) 2010, pp 11-14, May 2010
Publisher: New Zealand Institute of Forestry

---

Abstract: In New Zealand, wildling conifers threaten over 210,000 hectares of land administered by the Department of Conservation in the South Island alone. Currently, diquat is applied aerially at 3 kg/ha active ingredient in 400 litres per hectare total volume to control Pinus contorta. As this treatment is not very effective, the objective of this study was to evaluate if there are more effective alternative herbicide treatments to control P. contorta, P. mugo and Pseudotsuga menziesii. Alternative herbicide treatments and the current operational diquat treatments were applied during late spring in a pot trial in Rotorua. Except for diquat which was applied at 300 litres per hectare, all herbicides were applied in a spray volume of 150 litres per hectare. Percentage damage to the foliage of the trees was visually recorded in increments of 10%, prior to treatment and post treatment at monthly intervals, to a maximum of 190 days after the treatments were applied. A score of zero percent means no damage and 100 percent means the tree has died.

---