Combining weed efficacy, economics and environmental considerations for improved herbicide management in the Great Barrier Reef catchment area
Date
2020Metadata
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The current Australian sugarcane industry transition toward adoption of an ‘alternative’ herbicide strategy as part of improved environmental stewardship is increasingly complicated by recent farming system, regulatory and herbicidal product changes. This study quantified and compared the efficacy, economic costs and environmental risk profiles of a range of established, emerging, and recently registered pre-emergent herbicides across field trials in the Wet Tropics region of North Queensland. Several herbicides were effective on certain weed species, but lacked broad spectrum control. Better efficacy results from products with multiple active ingredients (i.e., imazapichexazinone) demonstrated the benefits of using mixtures of active ingredients to widen the spectrum of weed control efficacy. All tested pre-emergent herbicides behaved quite similarly in terms of their propensity for off-site movement in water (surface runoff losses generally N10% of active applied), with their losses largely driven by
their application rate. Herbicides with lower application rates consistently contributed less to the total herbicide
loads measured in surface runoff. Results demonstrated alternative choices from the more environmentally problematic herbicides (such as diuron) are available with effective alternative formulations providing between 4 and
29 times less risk than the traditional diuron-hexazinone ‘full rate’. However, considerable challenges still face
canegrowers in making cost-effective decisions on sustainable herbicide selection. Additional research and effective grower extension are required to address information gaps in issues such as specific weed control efficacy of alternative herbicides and potential blending of some herbicides for more effective broad spectrum weed control, while also minimising environmental risks. Extracted from Science of the Total Environment, 720 (2020)