Grains Research and Development

Date: 20.12.2015

Pre-harvest Herbicide Use fact sheet

Pre-Harvest Herbicide Use fact sheet cover page

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.

Key Points ––

  • Correct usage: Product labels must be followed and withholding periods adhered to for all herbicides. Off-label use without a permit is not allowed and can result in grain being unsaleable.
  • Residues: Pre-harvest applications to crops increase the risk of detectable herbicide residues in harvested grain, potentially leading to breaches of maximum residue limits (MRLs). MRLs vary according to herbicide, crop and market and these need to be understood. ––
  • Registration: Diquat, including Reglone®, is the only registered herbicide for preharvest weed control in barley. However, growers must be aware that some maltsters have certain restrictions on pre-harvest use of herbicides. Consult with buyers before use. weedmaster®DST® is now registered for pre-harvest use in canola and with higher use rates in wheat. It is the only glyphosate formulation registered for use in canola and for higher use rates in wheat. ––
  • 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 grain industry. ––
  • Be responsible: Stewardship must be taken seriously by all sections of the grain value chain.

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