Ontario Field Crop Report
2007 Corn Seasonal Summary

Table of Contents

  1. Summary
  2. Planting and Early Growth
  3. Growing Season
  4. Corn Pest Problems

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 2007 season from a corn perspective will go down as the year that could have been. More than 2.1 million acres of grain corn were planted; a near record, and the first time that acreage eclipsed the 2 million mark since 1985. The crop got off to an amazing start and the main challenge to the crop, and what prevented it from perhaps beating last year's record breaking yields was below average rainfall in most parts of the province. In the end, the provincial average corn yield will end up very close to 135 bu/ac, which is the 5-year average.

Planting and Early Growth

Excellent dry spring weather and good soil conditions resulted in an early corn planting start for most areas. The majority of the corn crop was planted April 25 to May 10. Generally, seedbed conditions were better than expected given the wet harvest and wheel-tracked fields from the fall of 2006. Uniform plant stands and good early growth were the norm in most of Ontario's corn fields as of June 1, 2007. By mid-June with the crop still looking good overall, dry soils started to highlight some nutrient deficiencies (Magnesium, Zinc, etc.) on lighter textured soils and/or where pH was out of balance.

Weed control from pre-emerge and post-emerge applications was generally good across the province. In situations were herbicides did fail to control weeds during the critical period (3-8 leaf stage) the crop suffered very significantly as the dry weather progressed on into July.

Growing Season

Precipitation was extremely spotty, but generally well below average in most regions. The exceptions to this were areas east of Kingston, and parts of Oxford and Perth counties. From May 1st to August 31st, 73% of normal rainfall was recorded compared to the 30-year average. Some areas received less than 25 mm in the period from May 1 to July 31. In many fields, the dry conditions seemed poised to significantly impact pollination. Generally, the crop set a reasonable ear (1/2 to 2/3 grain) even in some of the driest areas. The corn crop did benefit from a lack of extreme heat in July, (i.e., London only recorded three days over 30oC). Wilting of the crop certainly occurred during the day, but the lack of high heat stress did allow most fields to recover overnight. The exception to this was on the sands and heavy clays where available water simply could not keep up with crop demands and resulted in significantly reduced yields.

From May 1st to August 31st the average, across 15 Ontario weather stations, was 2570 CHU's in 2007. This compares to a 30-year average of 2544 CHU's. September and October added significantly to CHU totals in some areas and caused rapid lowering of both whole plant silage moisture and grain corn moisture. In some cases grain moisture fell 6 points in a single week. Nearly 200 CHU's accumulated at the Ridgetown performance trial site during the week ending the day after Thanksgiving. Heat unit accumulations of that level are usually reserved for the hottest week in July. For the most part, harvest moisture across the province was below normal and resulted in significantly lowered drying costs.

Ontario Corn Committee performance trials and grower experience in 2007 generally showed significant yield advantages for longer season hybrids. This advantage outstripped any increase in drying costs that resulted from higher harvest moisture. Growers seem to be generally pleased with the insect protection delivered by new genetic traits in last year's hybrids. There continues to be increased adoption of genetic traits for insect, disease and weed control across Ontario.

Corn Pest Problems

Corn was free from any significant insect and disease pressure in 2007. The lack of rainfall generally meant low leaf disease pressure in most areas. Although the province was not free of ear moulds and associated vomitoxins, instances were sporadic and modest, especially when compared to the experience of 2006.

Concerns were expressed in September that stressed plants trying to fill ears, might have cannabolized stalk tissue and lead to stalk rots and lodging. This did not occur and aided by generally favourable weather conditions in September and October, the crop stood quite well through to harvest.

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