Use of an organosilicone surfactant to minimise spray application volumes for forestry scrubweed herbicides in New Zealand

摘要

Weed control at forest establishment is undertaken predominantly by aerial application of herbicide sprays at 100 L ha~(-1)or higher and organosilicone surfactant addition is essential for achieving evenness and consistency of kill. Bioassays were used to compare the performance of sub-lethal doses of glyphosate and metsulfuron herbicides, applied separately in sprays of varying volume, on potted gorse and broom. A gantry tracksprayer was used to simulate aerial application. An organosilicone superspreader adjuvant improved the cost-effectiveness of scrub weed control by lowering spray application volumes by up to 75%. Maintaining a constant rate of adjuvant per ha in concentrated sprays (i.e. increasing the adjuvant concentration as spray volume decreased) provided control of gorse and broom better than, or equal to, typical high volume sprays. There are potential cost savings and efficacy benefits to be realised by use of low-volume, concentrated aerial herbicide sprays.