Glyphosate burnoff is registered and widely used for burnoff before and shortly after seeding many crops in western Canada. But if you use it this way for zero-till flax in heavy residue, it may be detrimental to stands and/or yield.

That's the finding of three years of AAFC research into low-disturbance seeding of flax into a high-residue cereal stubble, using three typical glyphosate burnoff timings. The brand of glyphosate you use does not matter - Vantage has the same effect as Roundup; Vantage* Plus the same as Roundup Transorb®.

Influence of glyphosate on flax 1996-1998

Mechanism of injury
Injury is caused to flax seedlings as they emerge through treated crop residues and stubble remaining from the previous year's cereal crop. Moisture conditions such as light rains or heavy dew can increase the injury. The cereal residue itself does not seem to be causing the injury, since in other studies of similar burnoff times with the residue removed, there was no injury.

Source:
"Flax as Influenced by Glyphosate", by Dave Berglund, NDSU extension agronomist, North Dakota State University Crop and Pest Report, May 10, 2001, p. 7.

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