Ontario Field Crop Report
2011 Corn Seasonal Summary

Table of Contents

  1. Summary
  2. Growing Season
  3. Corn Challenges
  4. 2012 Outlook

Technical information can also be obtained at the OMAFRA Field Crops Webpage and Crop Pest Ontario. Referenced OMAFRA Publications include the Agronomy Guide for Field Crops (Publication 811), the Field Crop Protection Guide (Publication 812), Guide to Weed Control (Publication 75), and Ontario Weeds (Publication 505). These can be obtained from your OMAFRA Resource Centre, or by calling 1-800-668-9938.


The 2011 corn growing season had a bit of everything; ugly, bad and excellent! Conditions early in the season were not conducive to planting, as April was relatively cool and May was significantly wetter than normal. Corn planting dragged on to mid-June in some parts of the province. Dry weather in July stressed the crop but August rainfall made for an excellent grain filling period. By the end of the season the Ontario Crop Heat Unit (CHU) accumulation was marginally above the 30 year normal for most locations in the province. For example, the CHU accumulation (May 1 to season-end) at London was 4% above normal, Mount Forest was 3% above normal and Ottawa was 6% above the 30 year normal.

Corn yields were surprisingly good - with about 50 % of the yields submitted to Agricorp, the provincial average yield stands at 161 bu/ac (10.1 tonnes/ha); when all acres are accounted for the provincial corn yield for 2011 will certainly be higher than the past five year average of 149.1bu/acre.

The 2011 harvested grain corn acreage will be approximately 1.85 million acres (749,000 ha). The relatively open fall coupled with high CHUs and reasonable harvest conditions meant that virtually all the crop was harvested before December 15.

Growing Season

April weather was abnormally cool and wet and afforded almost no opportunities for corn planting. The first window for corn planting was May 8-13; it is estimated that 60% of the total crop was planted at this time. May rainfall was above average in most areas of the province and corn planting after the 13th of May was a hit-and-miss effort. Significant corn acreage was planted in the first two weeks of June.

Rainfall was low throughout July in many areas. The last two weeks of July were particularly hot and dry, this coincided with corn pollination for all of the early planted corn and on some sandy soils kernel set was poor. However, for the vast majority of corn acres early August rains came in time to preserve kernel number and excellent growing conditions throughout August and September led to kernel size that was larger than average and often resulted in above average yields.

Killing frosts did not occur for most of the corn growing areas until well into October. This allowed for even the June planted corn to be harvested at grain moisture levels that were acceptable (i.e. 22-26%).


Early season weather conditions tended to reduce mineralization of organic matter or result in losses of N fertilizer through denitrification. The OMAFRA Pre-Sidedress Nitrate Test (PSNT) Survey done June 10-15 indicated soil nitrate levels that were below average. Research plots and producer fields tended to indicate above average N fertilizer requirements in 2011; most likely a combination of the three factors 1) reduced residual N from soil sources, 2) losses of applied N, and 3) increased demand from high yield corn crops.

Leaf and stalk diseases were generally quite low in 2011 however ear mould presence was above average and significant vomitoxin concern exists with the 2011 grain corn supply in certain parts of the province.

Western Bean Cutworm (WBC) continued to expand its range across Ontario in 2011. Average moth captures per trap nearly tripled compared with 2010 trap captures. Threshold was reached and control was required in isolated areas in Chatham-Kent, Lambton, Middlesex, Norfolk and Elgin Counties. In areas where eggs and larvae were present and feeding damage was observed, estimated yield losses approached 7 bu/acre or 3.4% yield loss.

2012 Outlook

Optimism is high for corn in 2012 due to the high productivity of the corn crop in the past two years. This is tempered somewhat by increasing input prices including fertilizer, seed, and land rents. Other areas of particular interest in 2012 include, 1) hybrid selection or fungicide application for improved ear mould and vomitoxin suppression 2) monitoring WBC development and in some areas focusing on hybrids that offer genetic protection, and 2) examining fertilizer input recommendations in the face of increasing yield expectations.

For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca