Ontario Field Crop Report
2008 Corn Crop Seasonal Summary

Table of Contents

  1. Summary
  2. Growing Season
  3. Leaf Disease and Ear Mould
  4. 2009 outlook

Technical information can 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 2008 growing season was characterized by adequate rainfall in nearly all parts of the province. A distinct lack of moisture stress and generally favourable conditions during flowering allowed for excellent pollination. Ontario Crop Heat Unit (CHU) accumulation was at or above the 30 year normal for the southwest but lagged considerably behind normal as you moved further north. For example, in the period May 1 to September 30, CHU accumulation at Windsor was 4% above normal, London 2% above normal and Barrie was 10% below the 30 year normal.

High Yields! With about 20% of reported yields submitted to Agricorp, the provincial average stands at 171 bu/ac. This number will most likely be reduced as more yields are reported, but it certainly appears that 2008 will set a new provincial grain corn yield record. Some counties are reporting average yields to date of over 190 bu/ac!

After relatively high total grain corn acreage in 2007 (2.1 million acres), the 2008 final corn acreage was approximately 1.8 million acres. November weather was not conducive to harvest and in some parts of the province 25% of the corn remains not harvested. Provincially the un-harvested acreage is estimated to be approximately 10%.

Growing Season

A favourable portion of late April weather allowed for a period of aggressive early planting with good soil conditions. In some areas producers completed planting by April 27. The vast majority of the crop was planted by May 8, but planting conditions did deteriorate for the mid part of May forcing some delays to near the end of the month for corn planting completion.

The 2008 growing season was below last years' accumulated Crop Heat Units (CHU's) but not far off the 30 year average. From May 1 to September 30, London reported 3,152 CHU's in 2008 compared to 3,262 CHU's in 2007. The 30 year average for London is 3,106 CHU's for that time period.

Frequent showers and windy conditions did prevent post emergence applications of herbicide on a significant acreage. Yield losses on these fields, although significant compared to weed free fields, were mitigated by adequate rainfall and low stress conditions that existed for much of the corn crop through the last half of June and all of July.

September was warmer than average in many parts of the province with the exception of those areas roughly north of Highway 7. The majority of the crop reached maturity before any killing frosts resulting in harvest grain moistures that were reasonable in most areas, although higher than the last few years.

Leaf Disease and Ear Mould

The persistent wet weather in certain parts of the province throughout the 2008 growing season, in conjunction with other factors such as leaf diseases, insect injury, or hail damage, raised concerns over the potential for corn ear moulds.

Ear mould survey results indicated that on average across the province, 26% of the ears sampled had some visual ear mould. However, on average DON concentration was 1.1 ppm and 85% of the samples were below the critical 2 ppm level.

As in previous years, the frequency of finding fields with DON levels above 2 ppm decreased as you went from southwestern to eastern Ontario. Microclimates and hybrid selection have consistently been important factors in predicting DON and mould problems and this year is no exception. Areas closer to the north shore of Lake Erie or Lake St. Clair tended to have the greatest number of fields above 2 ppm.

Fungicide applications on corn acreage continued to increase in 2008 with considerable interest in evaluating the impact on leaf diseases, plant health and yield. Strategies for the most efficient use of fungicides on corn are being developed. Hybrid appears to be a significant factor in predicting whether a fungicide application will have an economic impact.

2009 Outlook

Optimism exists in the corn sector due to the high productivity of the corn crop in 2008.

This is tempered somewhat by high fertilizer prices and grain corn markets that are lower than through most of the year. The following list suggests areas of particular interest to the corn industry in 2009.

  • Producers are looking to reduce P and K fertilizer costs in 2009 through extensive soil sampling and more targeted fertilizer applications;
  • Nitrogen management and cost control will remain a focus for the industry;
  • Maximizing the use of manure and extracting more value where possible will be a key;
  • Industry/producers will need to work towards a strategy for corn fungicide use that maximizes both potential economic returns and technology stewardship;
  • Strategies need to be adopted to eliminate yield losses due to delayed applications of post emerge herbicides (mostly glyphosate).

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