Pre-harvest herbicide applications

14/9/2026

Key actions before harvest

Check chemical labels, application timing and withholding periods (WHP).
Speak with your agronomist before pre-harvest applications.
Consider potential market access implications by commodity and destination market.

Pre-harvest herbicide application or “crop-topping” can be a good opportunity to reduce weed seed numbers for the following year.

However, because these applications occur close to harvest, growers need to carefully consider label requirements, residues and potential market access implications.

Product labels set the legal requirements for chemical use in Australia, and ensure Australian Maximum Reside Limits (MRLs) are not exceeded. However, WA grain is commonly exported to international markets that may apply different or lower MRLs. This means that legal use in Australia may still affect market access for some commodities or destinations.

Growers are encouraged to discuss pre-harvest herbicide options with their agronomist before application to choose the most appropriate course of action.

Registered products

Growers must only use products registered for the relevant crop and use pattern. This is a legal requirement and helps manage residue risk under Australian standards.

The tables included below state some of the registered products by crop, current as of August 2026. Note that the tables do not cover all commodities or products. Consult the individual product labels via the APVMA website to confirm registrations have not changed:

Public Chemical Registration Information System Search - portal.apvma.gov.au

Rates, timings and WHPs

Labels may have a rate range stated, applying at the minimum label rate required can help to minimise residues in grain. Application timing is always stated on the label and must be adhered to as this can have a significant impact on chemical residues in grain. Withholding periods (WHP) can be found below in the directions for use table and may differ between crop types.

Seed set management or harvest aid

Understanding whether the herbicide is being applied to control seed set of weeds or as a harvest aid either drying out weeds or crop will determine the most suitable herbicide for the planned task. For weed seed set control, the aim is not to kill the weed, but to sterilise the seed.

Glyphosate on barley: declaration on delivery

If glyphosate is applied to feed barley it is important to declare this on the CDF when delivering to CBH. This allows CBH to segregate glyphosate-treated feed barley where necessary.

Glyphosate is not registered to be applied to malt barley, and therefore any glyphosate treated barley will not be deliverable as malt grade. Maltsters and brewers require non-treated barley due to residues and germination issues.

Paraquat on barley: declaration on delivery

If paraquat is applied to lupins it is important to declare this on the CDF when delivering to CBH. This allows CBH to segregate paraquat-treated lupins where necessary.

For more detailed information refer to the product labels and consult with your agronomist.

Wheat

Active	Product example	Rate	Timing	Withholding period	AU MRL (mg/kg)	EU MRL (mg/kg)	China MRL (mg/kg)
Glyphosate	Roundup UltraMax	850 mL/ha - 3.4L/ha (570 g/L ai)	Late dough stage onwards (28% grain moisture)	5 days	5	10	5
Saflufenacil	Sharpen	34 g/ha + 1% MSO	Z71-83 (from watery ripe)	Refer to label instructions	0.2	0.03	0.01
Pyraflufen-ethyl	Sledge	200 mL/ha	Z71 onwards	Refer to label instructions	0.02	0.02	0.03
2,4-D	Amicide Advance	1.1-1.5L/ha (700g/L)	Apply after firm dough stage	Refer to label instructions	0.2	2	2

Barley

Active	Product example	Rate	Timing	Withholding period	AU MRL (mg/kg)	EU MRL (mg/kg)	China MRL (mg/kg)
Glyphosate Feed Barley Only*	Roundup UltraMax	1.65 L/ha (570 g/L ai)	Late dough stage onwards (28% grain moisture)	7 days	20	20	nil
Saflufenacil	Sharpen	34 g/ha + 1% MSO	Z71-83 (from watery ripe)	Refer to label instructions	0.2	0.03	1
Pyraflufen-ethyl	Sledge	200 mL/ha	Z71 onwards	Refer to label instructions	0.02	0.02	nil
2,4-D	Amicide Advance	1.1-1.5L/ha	Apply after firm dough stage	Refer to label instructions	0.2	0.05	nil

*Although glyphosate use for feed barley is now on label this still needs to be DECLARED at point of delivery.

Canola

Active	Product example	Rate	Timing	Withholding period	AU MRL (mg/kg)	EU MRL (mg/kg)	China MRL (mg/kg)
Glyphosate	Roundup UltraMax, Crucial	1.2-3.4L/ha (570 g/L ai)	20% seed colour change	Refer to label instructions	20	10	2

Active

Product example

Rate

Timing

Withholding period

AU MRL
(mg/kg)

EU MRL (mg/kg)

China MRL (mg/kg)

Glyphosate

Roundup UltraMax,

Crucial

1.2-3.4L/ha

(570 g/L ai)

20% seed colour change

Refer to label instructions

20

10

2

Lupins

Active	Product example	Rate	Timing	Withholding period	AU MRL (mg/kg)	EU MRL (mg/kg)	China MRL (mg/kg)
Paraquat	Paraquat 250	400-800 mL/ha (250 g/L ai)	80% leaf drop onwards	14 days	1	0.02	0.5
Saflufenacil	Sharpen	34 g/ha + 1% MSO	80% leaf drop onwards	7 days	0.2	0.03	0.3
Pyraflufen-ethyl	Sledge	200 mL/ha	80% leaf drop onwards	7 days	0.02	0.02	nil
Glyphosate	Crucial	600-1600 mL/ha	Full maturity 30% grain moisture	7 days	5	10	2

Other news

Glyphosate residues in canola 21/09/2026 Growers can minimise residues in grain delivered to CBH by considering the rate and timing of glyphosate applications to canola.
Paraquat use on lupins 08/07/2026 Based on extensive residue testing of grain and investigation into results, CBH has found some practical measures that can be taken by growers to minimise paraquat residues in lupin grain.
Pickled grain and contaminated loads 09/07/2024 Farm hygiene is key to preventing pickled grain contamination in grain delivered at harvest.