Pre-harvest desiccant – needed after a frost?

September 10, 2020 - Issue 26

A scenario: Canola is left standing for straight combining, and the field experiences a heavy frost. The farmer was going to give it a desiccant spray, but with the frost is that spray still necessary?

Analysis: Frost can actually benefit a canola crop that will be straight combined as the frost provides some extra dry-down of green stems. Frost at the point when pods are brittle and quite dried down will likely have little or no impact on the seed, and pod-shatter tolerance can also help maintain pod integrity if the crop wasn’t quite that dry yet.

We don’t really know how much frost (temperature, duration) would be equivalent to an application of diquat (Reglone), but we do know that in cool conditions, diquat may not actually work that well. As stated in the Canola Encyclopedia, “warm, sunny days following the application are ideal”.

Shared experiences from Canola Watch readers could help with our understanding. Do you wait for a frost before straight combining? Would you still use diquat after a frost, and why? If you have tips to share, please send us an email using this form.

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