The impact of drought and prolonged heat on corn and soybean yield is highly variable across the province, according to the 16th annual Great Lakes Grain Crop Assessment Tour.
The tour, organized in partnership with AGRIS Co-op, Central Ontario FS, Coop Embrun, and FS Member Co-ops, provides crop conditions and yield potential from 800 fields across Ontario. The results were released on the first day of Canada’s Outdoor Farm Show 2025.
Why it matters: Early-planted corn and uniform stands contributed to stronger performance, with crops across most counties appearing greener and slightly behind schedule in terms of maturity during the late August to early September yield tour.
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“For the most part, we have a crop, but we have some regions that were blessed with timely rains and some areas that definitely were not,” Devin Homick, Great Lakes Grain’s grain origination and business development lead, told Farmtario.
The average weighted corn yield prediction for Ontario is 186.4 bushels per acre; however, there were some significant outliers with Ottawa-Carleton averaging 209.1 bu./ac., Elgin County at 208.2 bu./ac., Essex County at 195.8 bu./ac. and Chatham-Kent showing 195.2 bu./ac. The other counties fell between 193.1 bu./ac. in Lambton County and as low as 148 bu./ac. in Simcoe County.
The Great Lakes Grain Crop Assessment used a 100,000-kernel-per-bushel count for 2025 to account for kernel depth shortfalls and other weather-related factors.
“When you get that drought, you start losing kernel depth and potentially test weight, because the crop didn’t have the nutrients to carry it all the way through,” explained Homick.
The tour report said early April-planted corn is well into the dent stage, with a 50 per cent milk line indicating physiological maturity and black layer formation within approximately 14 days. Meanwhile, corn planted in mid-May will need an additional 20-24 days to reach black layer. North Simcoe, which typically receives significant snowfall, experienced dry conditions this year despite planting into good conditions. “Then the taps just tuned off, and the problem is it was in the critical time of the corn crop, when you need that moisture for pollination, silking-tasselling time, because it allows those cobs to finish off properly.”
Homick said Central Ontario counties, plagued by extreme drought and heat, were not included in the yield counts and represent approximately 10 per cent of the province’s acres.
“Definitely, certain counties will have pretty high insurance claims,” said Homick. “There are some crops that are very poor, below their average yield.”
Sydney Lemoyre, Ottawa-Carleton and eastern county grain originator with Great Lakes Grain, said the corn showed slightly below previous years due to drought impact, but suggested many fields remain strong and could finish well with decent September weather.
“Soybeans were mostly average, with southern areas and lighter soils seeing some yield loss, while Embrun fields showed the best potential,” wrote Lemoyre in the report. “Pest pressure, including western bean cutworm, was minimal. Overall, despite challenging weather, eastern Ontario Crops are in good condition, and a solid harvest is still achievable.”
Chad Homick, East Elgin, Haldimand -Norfolk, South Oxford grain originator, said the area was “highly variable and largely disappointing” due to drought and heat taking a heavy toll, with “some corn ears dropping prematurely and spider mite damage evident in soybean fields, further pressuring yields.”
Historically, each soybean node would have three to four pods, but this year saw predominantly two.
“We use 2.4 to 2.5 beans per pod (calculation), we reduced that number to 2.2 – there just weren’t as many beans when we did our counts, per pod, as we normally like to see,” Devin Homick explained. “You’re talking bushels when you’re missing that factor from 2.5 to 2.2.”
Out of the 22 counties surveyed during the tour, four counties have yields of 40 bu./ac. or below, and six counties have yields above 50 bu./ac., with none reaching the 60 bu./ac. range, unlike in 2024.
“You offset a lot of rain, sometimes, with white mould and other disease challenges,” Devin Homick said. “This year, for the most part, we don’t have a lot of disease in the corn or bean crop, but at a cost of yield.”
