Pre-Harvest Glyphosate Staging Guide for Canola
Use this staging guide to confidently determine when your canola crop grain moisture is less than 30% and has reached the correct maturity for pre‑harvest glyphosate application.
Table of Contents
Glyphosate can be applied to canola for pre‑harvest weed control only when grain moisture is below 30% in the least mature areas of the field. This occurs at 50–60% seed colour change, including any areas of regrowth that may still be producing seed. Applying glyphosate at this stage helps manage late‑season weeds while protecting grain quality, marketability and compliance with maximum residue limits (MRLs).
What does 50–60% seed colour change mean?
Seed colour change refers to the proportion of seeds on the main stem that have changed from green to brown or black. This assessment should be made in the least mature parts of the field, not the most advanced areas.
At 50–60% seed colour change on the main stem:
- The top third of seeds are green, but firm to roll between your fingers
- The middle third of seeds are mostly brown, with some speckling
- The bottom third of seeds are fully brown or black
When these indicators are present, growers can be confident that grain moisture is below 30%, which is the minimum requirement for pre‑harvest glyphosate use.
Key indicators to look for
When scouting canola for pre‑harvest glyphosate timing, focus on these signs:
- 50–60% seed colour change on the main stem
- Seeds are firm and no longer watery when crushed
- Assessment includes regrowth areas and later‑maturing patches
- Crop maturity is consistent with grain moisture below 30%
- Application timing aligns with the product label and PHI requirements
Recommended harvest timing after application
Canola should be harvested 7–14 days after pre‑harvest glyphosate application, following label directions and the required pre‑harvest interval (PHI).
Never harvest earlier than recommended.
General information to help protect market access
- Where allowed, glyphosate is registered for pre‑harvest weed control only and must not be used as a desiccant.
- Glyphosate may only be applied when grain moisture is less than 30% in the least mature areas of the field, including any regrowth that could produce seed. Applying too early increases the risk of unacceptable glyphosate residues, which can lead to rejected loads and lost market access, especially for export markets with strict MRLs.
- Always follow the product label for application rate, timing and PHI.
- When using glyphosate in a tank mix (for example, with saflufenacil/Heat), application must still occur below 30% grain moisture and follow the most restrictive PHI on the tank‑mix labels.
On‑farm decisions play a direct role in protecting Canada’s reputation as a reliable supplier of high‑quality canola.
FAQs
When can glyphosate be applied to canola before harvest?
Glyphosate can be applied only when grain moisture is below 30%, which corresponds to 50–60% seed colour change in the least mature parts of the field.
What happens if glyphosate is applied too early?
Applying glyphosate before grain moisture is below 30% can result in unacceptable residue levels in harvested grain, which may lead to non‑compliance with market and regulatory requirements.
How long after spraying glyphosate can canola be harvested?
Harvest should occur 7–14 days after application, and never earlier than the product’s stated PHI.
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