Is a second fungicide pass worth it in canola?
Single pass at 20-30% bloom versus a two-pass program.
Producer field, West Central SK · Producer identity withheld
The question
In a season with average sclerotinia risk, does a second fungicide application return more than the product and pass cost?
Two-pass programs are widely recommended, but recommendations are written for high-risk seasons. This producer wanted to know what the second pass is worth in an ordinary year on their own ground.
Trial design
How it was run
- Field split lengthwise: single pass at 25% bloom on one half, second pass seven days later on the other.
- Risk assessment run at both timings; petal test and canopy moisture recorded.
- Harvested with a single combine, both halves weighed separately over a scale.
Results
What the numbers did
What if prices change?
Yield and rates are fixed observations from the field. Move the price and cost assumptions to see whether the result still holds on your farm.
| Treatment | Yield | Revenue/ac | Cost/ac | Margin/ac |
|---|---|---|---|---|
| Single passControl | 52.6 | $710.10 | $199.00 | $511.10 |
| Two pass | 53.1 | $716.85 | $235.00 | $481.85 |
At these assumptions the treatment returns −$29.25/ac against the control.
The story
What the season looked like
Petal testing at first application showed moderate infection pressure. The week between passes stayed dry and hot, which pulled risk down sharply.
Disease scouting at swathing found low sclerotinia incidence in both halves — 3% in the single-pass, 2% in the two-pass.
The yield difference was inside the noise of the scale tickets.
What we learned
Takeaways
- 01The second pass bought roughly a percentage point of disease control in a low-pressure week.
- 02In this season it did not pay. In a wet bloom period the same decision could look completely different.
- 03The value is in the risk assessment at timing two, not in booking the second pass in advance.
Would we do it again?
Not this year.
Keep the second pass as a decision, not a plan. The economics turn entirely on canopy moisture in the week after the first application.
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