Pre-harvest Herbicide Use fact sheet
Published: 13 Oct 2017
Stewardship for pre-harvest application of herbicides in winter crops
The responsibility to avoid herbicide residues in delivered cereal, pulse and oilseed grains sits squarely with grain growers and their advisers.
Pre-harvest herbicide use
The application of herbicides late in the season to prevent weeds setting seed or to desiccate crops must be carried out with caution and in line with herbicide label recommendations. It is essential to check if these practices are acceptable to buyers, as in some situations markets have extremely low or even zero tolerance to some pesticide and herbicide residues.
Product labels must be followed and withholding periods adhered to for all herbicides.
- Application of herbicides close to harvest increases the possibility of detectable herbicide residues being present in harvested grain.
- Maximum residue limits (MRLs) vary according to herbicide, crop and market. Compliance with Australian MRLs does not guarantee the grain will meet an importing country’s MRL. It is important to know the destination of your grain and to check both domestic and importing countries’ MRLs to determine what herbicides are permitted on that crop. Breaches of MRLs can lead to rejected grain both domestically and by the importing country.
- Grain handlers and marketers regularly conduct surveillance on grain receivals for residues. The National Residue Survey also conducts ongoing residue testing of grain.
- Late season herbicide use must strictly comply with the registered label to ensure Australian MRLs are not breached.
- Growers should seek advice from their grain buyers before using late applications of herbicides. This is very important for seed that is intended for sprouting.
- Barley: Diquat (e.g. Reglone®) and Sharpen® are the only herbicides registered for pre-harvest weed control in barley, however a minor use permit for certain glyphosate formulations is currently available for use on feed barley only. Growers must be aware that some barley maltsters have restrictions on all pre-harvest use of herbicides. Consult with buyers before use.
- Registrations for glyphosate use on cereals and canola vary across different labels (see table 2 within Factsheet).
- Sharpen® (saflufenacil) has been recently registered for late-season application in pulses and cereals.
Growers and their advisers need to be aware of the implications of their herbicide applications and the role they play in ensuring food health safety and in protecting the grain industry.
Stewardship must be taken seriously by all sections of the grain value chain.
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