2022 Corn Seasonal Summary

Black tar spot fungal structures (stromata) on leaves in a field near Ilderton in late September 2022.


In March 2022, Statistics Canada estimated Ontario farmers intended to plant 2.3 million acres of grain corn, 6% higher than the 5-year (2017-2021) average seeded acres of 2.16 million acres (OMAFRA Crop Statistics).

Spring arrived slow. Lingering snows and rain limited field work on all but the lightest soils in late April. A very small amount of corn was planted between rains by the first week of May, but planting did not start in earnest until the week of May 8. Once started, pace was extremely fast. Many retailers reported this to be the busiest week of their careers. By the following week (May 15) most of the corn was reported to have been planted except for on heavier or poorly drained soils which were mostly planted the last week of May.  

With sunshine dominating the forecast, many growers reported waiting an extra day or two for soil conditions to be fit before starting planting, not feeling the pressure to push soil conditions as they may have in recent years. Towards the end of the planting window, there were some concerns about seedbed moisture in fields that were over-worked or worked well ahead of planting. Given the warm, sunny conditions, corn emerged very quickly – as little as 6-7 days in some cases. Many fields were emerged by the Victoria Day long weekend (May 21).

Final grain corn planting estimates for the province were 2.28 million acres (OMAFRA Crop Statistics), similar to the March planting intentions and slightly higher than the 5-year average.

Early Season

Field crop staff typically complete a Pre-Sidedress Nitrate Test (PSNT) survey in early June each year. Given increasing difficulties finding fields meeting survey criteria (no upfront Nitrogen (N) applied), this survey was not completed in 2022. Staff will investigate other options for providing guidance on in-crop nitrogen decisions. 

Optimum fertilizer N rates are a function of N supply (soil N mineralization minus N losses) and demand (yield). Given dry conditions, N losses from saturated soils (denitrification, leaching) would be expected to be minimal in 2022. Losses from urea-based fertilizer placed on the surface with minimal rain can be high. Research from the University of Guelph has demonstrated optimum corn N rates to be highly correlated to rainfall from mid-June to mid-July – rainfall during this period was highly correlated to yield and thus N demand. Where N was placed to minimize volatilization losses and yields were slightly less than normal due to dry weather, N requirements were likely lower than normal in 2022. On-farm N trials can help confirm actual N requirements (https://bit.ly/3Wixx9l).   

June was favourable for in-crop management. Some side-dressing started by the beginning of June and was in full swing by the start of the second week (June 12). Many fields were closing rows by the following week (June 19). A stretch of very cool night temperatures, including frost in some low-lying areas was reported around this same time. Crop impacts were minimal.

By late June most of the crop looked good but moisture stress (e.g., leaf rolling) was evident on soils with poor moisture holding capacity (Figure 1). Symptoms progressed where rainfall remained limited through July. Moisture stress was less of an issue through Central and Eastern Ontario where more regular rains were received.

Figure 1. Variable corn under moisture stress in a field with poor moisture holding capacity near Ridgetown, July 15.
Figure 1. Variable corn under moisture stress in a field with poor moisture holding capacity near Ridgetown, July 15.

Pollination and Grain Fill

Corn started tasseling in earnest the week of July 17 with the following week (July 24) likely being the major week for tasseling and pollination. Dry conditions persisted for many, and field variability was evident as tassel emergence was not uniform in moisture stressed fields. There was significant concern given this is the most sensitive time for yield loss due to moistures stress.

Regular scattered rains were received in many areas through August. Several weeks brought general instability and scattered showers. The pollination window was largely missed, so these rains were very welcome. Western bean cutworm (WBC) moth flights were similar to 2021 where peak flights occurred the last week of July or first week of August. This is slightly earlier than traditional peak moth flights and would have coincided with the latter end of corn tasseling.


Earlier corn silage harvest generally started around the first week of September. Harvest was in full swing the second and third full weeks of September in many areas. Statistics Canada estimated 218,000 acres of corn silage were harvested, lower than the 5-year average of 275,000.

The annual ear mould and DON (vomitoxin) survey was completed September 28to October 5. The purpose of the survey is to measure the relative levels of DON in the grain corn crop just prior to harvest to provide information for growers and industry. A total of 193 samples were collected across the province. Visual mould and DON levels were among the lowest in the history of the survey, with 98% of samples testing low (less than 2.00 ppm). Higher testing samples were generally well distributed across the province, with some more concentration in the far southwest. As in most years, even those with low risks, there was still reports of elevated fields, so monitoring is always suggested. Final report is available at Fieldcropnews.com (https://bit.ly/3Hw1kaj).

Insect feeding damage was very low in 2022 survey samples. Most corn tasseled just before peak western bean cutworm moth flights. Mould symptoms were more apparent where feeding damage was present.

Some high moisture or early harvest grain corn started by the first week of October. Harvest started in earnest by the middle of October. Sunshine and well above normal temperatures dominated and made for beautiful harvest conditions. Harvest was rapid once started, with few weather events to slow progress. Weather also provided excellent ground conditions and in-field drying. By the end of the first week of November, the majority of crop was off in many areas.    

Like most dry years, yields were highly variable. On soils with very poor moisture holding capacities, there were reports of yields under 100 bu/ac. Outside of those areas, many growers reported yields lower than the past couple years but better than expected in July or August. In areas that did receive sufficient or timely rains, excellent yields were often reported.  

Reports of DON at harvest were generally low. Dry conditions were expected to limit inoculum production. Dry conditions at silking likely limited ear establishment. Some high testing fields were reported in the far southwest, likely a function of hybrid susceptibility and moisture received during periods sensitive for ear mould establishment/growth.    

Estimated grain corn yield for Ontario is 166 bu/ac (OMAFRA Crop Statistics), 2% higher than the 10-year average of 163 bu/ac (2012-2021). The 2022 Ontario hybrid corn performance trials results are available at the homepage of gocorn.net or https://bit.ly/3FLrZ1o. Several options exist for viewing data, including printable PDF, sortable spreadsheets (yield index, moisture, lodging, company or hybrid name etc.) and yield by moisture graphs demonstrating the trade-off between yield and harvest moisture of hybrids within each OCC table.

Things to Watch in 2023


First observed in Ontario in 2020 near Ridgetown, tarspot has successfully overwintered and is now established in the province. Spread by wind-blown spores, black fruiting structures (stromata, Figure 2) could be found in corn in all counties west of Toronto in 2021. Given the very dry conditions in 2022, disease development and spread were limited, but could be found in some fields. Growers should remain vigilant. Whether tar spot becomes an issue in 2023 depends on weather conditions. Cool and humid canopies with prolonged leaf wetness like 2021 are favourable for development. Infections are most severe in corn-on-corn fields where tarspot was present in the past. Corn residue serves as a source of inoculum for earlier infection in those fields. Ontario research is looking at hybrid tolerances and fungicide management options. For more information, see resources at CropProtectionNetwork.org.

Figure 2. Black tar spot fungal structures (stromata) on leaves in a field near Ilderton in late September 2022.
Figure 2. Black tar spot fungal structures (stromata) on leaves in a field near Ilderton in late September 2022.

Corn Rootworm

In recent years, corn rootworm larvae feeding in fields with corn rootworm Bt protection has raised concerns about Bt resistance. This is generally in or near fields with corn-on-corn rotations and repeated use of corn rootworm Bt hybrids. Fields with injury have been observed in several counties the last couple years. Growers with histories of corn-on-corn rotations using corn rootworm Bt hybrids should monitor fields for excessive corn rootworm beetle populations, lodging or goose-necking plants. Rotation out of corn is highly recommended in these fields. For more information, search “corn rootworm” at FieldCropNews.com.