Research Branch Report No. 261
Weedicides for removal of natural regeneration of radiata pine in second-rotation plantations. G. Minko and L. A. Stephens. October 1984. 7 pp. (unpubl.)
SUMMARY
Results are reported from a study carried out between 1979 and 1983 near Myrtleford in North-eastern Victoria, of the effectiveness of chemical sprays in controlling (killing or permanently stunting) unwanted natural regeneration of radiata pine (Pinus radiata D. Don), appearing after clearfelling of mature stands.
Effective control of individual stems resulted when the foliage was sprayed to drip-off point in spring with any of the following chemicals: amitrole plus ammonium thiocyanate as WEEDAZOL TL† at 70 mL, dicamba as BANVEL 200† and VELSICOL 4092† at 63 mL, fosamine ammonium as KRENITE† at 125 mL, glyphosate as ROUNDUP† at 50 mL, and paraquat as GRAMOXONE† at 12 mL, each in 1 L water carrier to make up a spray. Higher rates of the same chemicals were also effective when applied at other times of the year.
For the control of 1-2 m tall thickets of radiata pine natural regeneration, fosamine ammonium applied as KRENITE† at 125 L ha-1, plus 1 000 L ha-1 water carrier, produced the best result. Dicamba at 125 L ha-1 and amitrole plus ammonium thiocyanate at 140 L ha-1 were less effective. Being a contact weedicide, fosamine ammonium failed to control smaller trees shielded in the thickets by adjacent stems. Thus, this chemical must be applied when the trees are small and the thicket canopy is open.
At present, the high cost of fosamine ammonium, at effective rates (about $1 860 ha-1), limits its usefulness in the control of radiata pine thickets. Further work is therefore necessary to increase its effectiveness and thereby reduce the cost of treatment.
†Registered Trade Name. Trade names are used for the convenience of the reader. Such use does not constitute an endorsement of any product to the exclusion of others that may be equally suitable.
Also published:
Minko, G. (1985) Herbicides for removal of natural regeneration of radiata pine in second-rotation plantations. Plant Protect. Qrtly 1 (2): 67-70.