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Aquatic fate of aerially applied hexazinone and terbuthylazine in a New Zealand planted forest

Posted date: April 15, 2015
Publication Year: 
2015
Authors: Baillie, Brenda R.; Neary, Daniel G.; Gous, Stefan; Rolando, Carol A.
Publication Series: 
Scientific Journal (JRNL)
Source: Journal of Sustainable Watershed Science and Management. 2(1): 118-129.

Abstract

Herbicides are used to control competing vegetation during tree establishment, and are often critical to the productivity and economic viability of a planted forest crop. Despite increasing public concern over herbicide use in planted forests and potential impact on the environment, there is limited information on the aquatic fate of many of these herbicides when applied in forests according to standard operational procedures. Two herbicides commonly used in New Zealand's planted forests, terbuthylazine and hexazinone, were aerially applied during two consecutive years at 7.4 kg and 1.1 kg ha-1 respectively, to a 12.5 ha catchment of newly planted Pinus radiata (Radiata pine) in the Bay of Plenty region of New Zealand. One hundred percent of the area was sprayed during Year 1 while 85% of the area was sprayed during Year 2. The highest concentrations of both herbicides were measured in stream water, sediment and algal samples on the day of herbicide application during Year 1 (September 2012 to June 2013), mainly as a result of spray drift, and in stream water during Year 2 (September 2013 to April 2014) at the time of a rainfall event seven days after herbicide application. Terbuthylazine concentrations exceeded New Zealand and World Health Organisation drinking water standards for

Citation

Baillie, Brenda R.; Neary, Daniel G.; Gous, Stefan; Rolando, Carol A. 2015. Aquatic fate of aerially applied hexazinone and terbuthylazine in a New Zealand planted forest. Journal of Sustainable Watershed Science and Management. 2(1): 118-129.