Efficacy of endothall dimethylalkylamine salt applied to static irrigation channels during winter to control aquatic weeds in temperateAustralia

摘要

Options for controlling aquatic weeds in irrigation channels are currently limited in Australia. A potential control option to enable efficient delivery of water is to apply endothall dimethylalkylamine salt to static irrigation channels ponded in temperate winter conditions, when long exposure times can be achieved. This article reports on a mesocosm dose-response experiment and field experiments to determine the efficacy of endothall dimethylalkylamine salt against five aquatic weed species (Vallisneria australis, Potamogeton sulcatus, Elodea canadensis, Sagittaria platyphylla, and Myriophyllum papillosum) that obstruct irrigation channels in Australia. Concentration-exposure time (CET) relationships were determined for each species in a mesocosmtrial (~10 C water temperature). Effective control required long exposure times (7 to 21 d) and generally; high concentrations (2.4 to 4.8 mg ae L_1) for all species, except E. canadensis, which was not controlled at any rate. Field trials in irrigationchannels (~10 C; 35 to 36°S) subsequently demonstrated effectiveness against V. australis (3.4 mg ae L_l), S. platyphylla, and M. papillosum (5 mg ae L_1) at exposure periods of 20 to 30 d. Estimated biomass reductions were 46, 91, and 98, 19 wk after treatment period, for V. australis, S. platyphylla, and M. papillosum, respectively. These biomass reductions resulted in improved operation of irrigation channels and delivery of irrigation water. We conclude that endothall dimethylalkylamine salt applied with long exposure times to static irrigation channels ponded during winter conditions provides an effective tool to reduce aquatic plant biomass and subsequently enables efficient delivery of irrigation water in temperate Australia. These results demonstrate a new use pattern for endothall dimethylalkylamine salt.