Corn School: Will your corn reach maturity?


Is the corn going to make it? Will it mature before Ontario farmers are greeted by the first killing frost?

Those were the two big questions that dominated conversations at Canada’s Outdoor Farm Show this week in Woodstock, Ontario. To get a good understanding of the challenges the provincial corn crop is facing, RealAgriculture sent agronomist Peter Johnson out to scout fields and look for evidence of the huge variability farmers are seeing in the slow maturing crop.

On Sept 12, corn in Ontario should be at the half milk line stage.

In this episode of the Corn School, Johnson tells Bernard Tobin that he looked for four hours before finding a field of corn at half milk line (the maturity stage the crop should reach by Sept 12). At this stage the crop requires 12 to 15 days to reach black layer and physiological maturity.

Johnson says he found an alarming number of fields that were still in the milk stage where kernels had no dent and will require up to 35 days to reach maturity. He also observed many fields where cobs were at early dent stage and could require up to another 30 days.

Obviously, the potential for a killing frost could quickly end the race to maturity, but the cold nights of early September have also been producing cold shock that can halt starch accumulation for up to two to three days before the plant can rebound and restart. Johnson explains that these disruptions can stretch out the grain fill process even further and significantly increase the days required to reach maturity.

So, will all this corn mature? It will come down to the weather, says Johnson who stresses that he’s an agronomist, not a meteorologist. “If I knew the weather, I wouldn’t be worried about black layer, I would go play the markets.”

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