Wheat School: What is a pre-harvest interval and why does it matter?


When looking at any pesticide label there should be three words that make you stop, think, and mark the calendar: pre-harvest interval.

The pre-harvest interval — PHI — is the minimum time necessary between application of a product and cutting the crop, either by swathing or straight-cutting.

As Sheri Strydhorst explains in this RealAgriculture Wheat School video, there is one more detail to consider: proper timing of application.

Strydhorst, of Sheri’s Crop Consulting, says the PHI refers to the number of days required when the product is used in accordance with label rates, frequency and the proper timing of application. She notes that some producers may run in to issues when a pre-harvest pass of glyphosate is done when the crop is at 40 per cent moisture versus 30 per cent moisture.

Adhering to the PHI and the proper timing of a pesticide pass is critical for crop quality and export readiness — Canada’s export markets for cereals and oilseeds is just too valuable to risk, she says.


Poll: More, less or the same — a pre-harvest pass

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