OMAFRA Field Crop Report – August 10, 2022

Poor corn development due to dry weather stress.


Much of the province received rain this past week, with significant rainfall (over 76 mm or 3 inches) in Huron Shores and Georgian Bay and eastern Ontario. A 25 to 50 mm (1-2 inch) rain mid-summer can still help finalize average yields, but it is too early to make final yield predictions. Crops that will benefit most are hay, pasture, corn, longer day soybean varieties, and forage and cover crops seeded after cereal harvest.

Figure 1. Percent of average precipitation (mm) in past 30 days, as of August 8, 2022.
Figure 1. Percent of average precipitation (mm) in past 30 days, as of August 8, 2022.


Most of the winter wheat acres have been harvested. Yields are average to above average this year (between 90-110 bu/acre), but some variability with some fields yielding over 140 to low 70’s on sandy soils, and quality has been excellent for the most part. Spring wheat stands are in good condition as harvest approaches over the next few weeks. Yields are expected to be average across the province. There are some concerns with plant stress due to lower rainfall amounts in the southwest and lodging in eastern Ontario.

Edible Beans

Overall, edible beans are progressing well. Disease pressure has been low due to dry weather in most regions.


Soybean growth continues to be varied across the province as we enter mid-August pod set and pod fill stages. Soybeans will benefit from these recent rains which should reduce the spider mite pressure. Disease pressure remains low, although Sudden Death Syndrome infected areas in fields in the southwest have become more prevalent as the crop matures.


A large amount of the province’s corn has been tasseling and pollinating over the past couple weeks, a stage when crop stress tends to have the biggest impact on yield. Corn is highly variable across the province, with many fields in good condition except in the exceptionally low rainfall areas and lighter sandy soils, where crop stress is evident by variable height and staging. Some yield loss is be expected in these fields due to unrelieved stress at this point in maturity. Final yields still depend on rainfall through remainder of the season.

Figure 2:  Poor corn development due to dry weather stress.
Figure 2:  Poor corn development due to dry weather stress.

Silage Corn

Several growers are considering selling drought stressed corn as silage off the field to local livestock producers. Some factors to consider include potential grain content and removal of crop residue and fertility from the field in the form of the leaves, stalks and cobs in addition to the grain. It is also difficult to estimate silage yield and moisture.  Samples should be taken before harvesting the field to determine the whole plant moisture. For proper silage fermentation and storage, the recommended silage moisture content should be:

  • horizontal bunker silos: 65%-70%
  • tower silos: 62%-67%
  • bag silos: 60%-68%

Yields are best determined by weighing a few loads as they come off the field and adjusting to dry matter content (0% moisture).  For more information, visit Field Crop News.


This most recent rain will significantly help new growth on the alfalfa and grasses for hay and pasture. Alfalfa in the full flower stage will not grow anymore and should be cut to stimulate new growth. Note that forages, including corn silage, harvested immediately after a rainfall following dry weather stress can be high in nitrates resulting in livestock poisoning and silo gas. This is particularly high risk during the 5 – 7 days following a rain that ends a severe dry period.  Silo gas can be fatal to both humans and livestock.  Extra caution should be taken around silos, feed rooms, etc. and keep these areas well ventilated after silo filling. For more information, see factsheet on Potential Nitrate Poisoning and Silo Gas When Using Corn Damaged by Dry Weather for Silage, Green Chop or Grazing.

Cover Crops

There is still time to seed some cover crops.  See the Field Crop News Article Cover Crops Following Cereals and Late Summer Harvested Crops for some options. Keep in mind, many of the cover crops can be used as emergency forages such as oats and oat mixture, fall rye and red clover under-seeded in the winter wheat crop to name a few.

Weather Data – August 1 – 7, 2022

LocationYearHighest Temp (°C)Lowest Temp (°C)Rain (mm)Rain (mm) April 1stGDD 0C April 1stGDD 5C April 1stCHU May 1st

10 YR Avg. (2011-20)27.716.410.4390215915172361
10 YR Avg. (2011-20)27.414.726.7363203113932199
10 YR Avg. (2011-20)27.414.416.7358201013772182
10 YR Avg. (2011-20)27.514.412.4334202013852198
10 YR Avg. (2011-20)26.811.820.8359181211921951
Mount Forest202226.616.91.5262170711511793
10 YR Avg. (2011-20)26.412.621.6368179311801952
10 YR Avg. (2011-20)27.611.630.4330184012191956
10 YR Avg. (2011-20)28.113.613.7342193213122084
10 YR Avg. (2011-20)25.710.722.1304155510181729
10 YR Avg. (2011-20)26.712.819.9332166611071852
Thunder Bay202223.711.20.041013298281391
10 YR Avg. (2011-20)25.610.210.532114689191585
Fort Frances202224.013.50.052314069081539
10 YR Avg. (2011-20)
Report compiled by OMAFRA using Environment Canada data. Data quality is verified but accuracy is not guaranteed. Report supplied for general information purposes only. An expanded report is available at