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.
- 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
- 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
- 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
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