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Impact of frost in Southern Ontario the hot topic

May 12, 2010 -A bi-weekly meeting of crop advisors and provincial extension personnel acknowledged concerns regarding crop health across much of south-central Ontario in the wake of freezing temperatures across much of the reason, this past weekend. 


May 12, 2010
By Top Crop Manager

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May 12, 2010 –The regular meeting of certified crop advisors and Ministry of Agriculture, Food and Rural Affairs specialists on Tuesday in Exeter, Ontario, fielded many concerns and observations following a weekend frost event that was widespread across the prime agricultural counties of Ontario.

About 25 advisors and specialists attended the morning meeting and heard that temperatures across the region varied from minus two degrees C to minus 10 degrees at one station near Strathroy, Ontario.

In corn, the damage will be greatest in those later planted fields, but generally, conditions should be fine as the growing point is still below ground, out of range of the frost. With early-planted soybeans, the observation was that few fields have been planted, and those that had emerged might have suffered some damage. But the conclusion was that it was a small acreage that might have been affected.

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On winter wheat, the crop across Ontario is widely acknowledged to have been the best to emerge from winter in several years, so concern is that if it’s in the late boot stage, it can withstand less frost stress (two hours at minus two degrees C) than if it’s in mid-boot stage (four hours at minus two).


Above all, farmers and their advisors and dealers need to get out and scout their fields, check for damage and assess the real need for replants.

Also with the wheat crop, many fields across the region (Middlesex, Huron-Perth, Oxford) saw an virtual explosion of mildew last week, so the time for fungicide applications is now, and in some fields, will actually be too late. Continued cool weather will delay mildew’s disappearance. And just as they did in 2009, wheat growers are seeing a lot of corn row syndrome, with manganese-deficient wheat in between those rows. Peter Johnson, provincial cereal specialist also said he’s seeing signs of magnesium deficiency and one field with copper deficiency. Growers need to determine what is deficient and correct the situation.


As for herbicide spraying on wheat, that time is now past; the flag leaf is out. Any herbicide spraying now is just "for revenge," said Johnson.