Wheat School: Harvesting highly variable winter wheat

Ontario’s winter wheat crop has been fighting an uphill battle ever since last fall and the struggle will likely continue right through to harvest.

On this episode of the RealAgriculture Wheat School, agronomist Peter Johnson explains that the highly variable crop will likely mean harvesting headaches. Last week at the University of Guelph’s Ridgetown College Diagnostic Days, Johnson noted that throughout the province he’s seeing fields with main heads well advanced into the grain fill stage, while the lower canopy is full of late tillers with few seeds per head.

“When the main stems are mature the tillers will be green seed,” he says, and that could lead to quality issues. If growers harvest early the green seed will be part of the sample; if they delay harvest to wait for tillers to mature they could compromise the quality of the main heads and have their wheat downgraded.

Johnson says growers have several options. He notes it’s important to remember that most of the yield is in the primary heads, so it doesn’t make sense to wait on tillers and risk compromising the quality of the majority of your yield. (Story continues after the video.)

With straw commanding a premium, Johnson acknowledges growers will want to maximize tonnage, but if the crop is cut too low all those laggard tillers will be in the sample and lead to grade deductions. One alternative is to cut high at harvest and then make a second cut for straw.

Pre-harvest glyphosate is another option. Here again, the challenge is the wide range of crop variability. Johnson says it’s critical for growers to wait for the peduncle to change from a green to yellow colour. This ensures that no glyphosate will translocate into the grain. “We want 100 per cent of the peduncles changing colour before we spray glyphosate,” he says, “but then we risk the main heads going off quality.”

In the end, it will likely come down to the weather. “If rain is coming you may have to take what you can and take the straw later….If it stays dry you can wait on the late-developing heads.

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