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.

Key Points

Correct usage: Product labels must be followed and withholding periods adhered to for all herbicides.

Residues:

• Application of herbicides close to harvest often will result in detectable residues 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

Key registrations:

• Paraquat is not registered for use in cereal or canola crops
• Barley: Diquat (e.g. Reglone®) and saflufenacil (Sharpen®) are the only herbicides registered for pre-harvest applications in both feed and malting barley. Roundup Ultra® Max is registered for use in barley (except malt barley). 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)
• Saflufenacil (Sharpen®) is registered for late-season application in pulses and cereals
• Paraquat (Gramoxone®) is registered for late-season application in winter pulses only.

Food safety: 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 grains industry

Be responsible: Stewardship must be taken seriously by all sections of the grain value chain