Black layer countdown: Can we go frost-free until late October?


Corn needs about 55 to 60 calendar days to go from tassel to black layer… but that holds true, generally speaking for Ontario, if tasseling happens in mid-July.

RealAgriculture resident agronomist Peter Johnson says that because that 60 “days” is really a measure of heat accumulation, hitting black layer when tasseling starts in early August and, in some cases this year, mid-August, it could take all the way until late October for this corn crop to reach full maturity.

The 60 day time period can stretch from 65 or 70 or even more calendar days, Johnson says, because September is historically cooler, night time temperatures dip lower, and total sunlight hours are reduced.

The Ontario corn crop has come through pollination in fine shape, Johnson adds, but farmers will be holding their breath for a long, open fall, with — fingers crossed — a killing frost holding off until mid to late October.

Related: When a day isn’t a day in corn

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