Author Archives: Pam de Rocquiny

Estimating Date of Grain Corn Maturity from Silking Stage

Silking marks the start of the reproductive phase of development and begins when the silk becomes visible outside the husk and pollination occurs. Each silk is attached to an ovule which will become a kernel if pollinated. The CHU accumulation from planting to silking is about 50 to 55% of that required for the plant to go from planting to physiological maturity.

While this could be used as a general guideline, temperature and relative maturity of the hybrid must be taken into consideration. Plus, the duration of each stage during grain fill can also be influenced by soil fertility, cultural practices (plant populations), and moisture.

If we consider CHU accumulation and maturity rating of the hybrid, we can calculate the number of corn heat units required for a crop to pass from silking to physiological maturity. As mentioned above, the period from planting to silking takes approximately 50 to 55% of the total heat units required for the crop. Therefore, the remaining 45 to 50% would be needed to carry the crop from silking to physiological maturity. The table below identifies the approximate CHU requirements to bring a corn crop from silking to physiological maturity based on a range of CHU maturity ratings.

Table 1: Approximate Corn Heat Unit (CHU) Requirements from Silking to Physiological Maturity for Various Hybrid Maturities.

CHU Rating of the HybridApproximate CHU Required from Silking to Physiological Maturity
2100945 to 1050
2200990 to 1100
23001035 to 1150
24001080 to 1200
25001125 to 1250
26001170 to 1300

Once a crop’s CHU requirement from silking to physiological maturity is determined, the next step is to establish the number of CHU that can reasonably be expected from the date of silking until the end of the season.  Referring to Tables 2 and 3 (where dates of expected additional CHU accumulation from two silking dates in the season), we can estimate the approximate date when a given accumulation of CHU past silking is reached.

For example, if the silking stage of a 2200 CHU hybrid grown near Morden occurred around July 18, the crop would require approximately 990 to 1100 CHU to go from silking to physiological maturity (see Table 1 and use 1100 for simplicity).  According to Table 2, the accumulation of 1100 CHU starting July 18 would occur by approximately September 5 in Morden.  It is important to keep in mind that these numbers are estimates based on historical observations.  Some years will have temperatures above or below average, causing the dates to shift forward or back.

Table 2: Date of Expected CHU Additional Accumulation from July 18 at Various Manitoba Locations (Source: Environment Canada averages 1971-2000).

From July 18+900+1000+1100+1200+1300
Elm Creek28-Aug03-Sep09-Sep17-Sep27-Sep

Table 3: Date of Expected CHU Additional Accumulation from July 25 at Various Manitoba Locations (Source: Environment Canada averages 1971-2000).

From July 25+900+1000+1100+1200+1300
Elm Creek08-Sep15-Sep25-Sep08-Oct

Remember that this is only estimating time from silking to physiological maturity, not when harvest can start.  Field dry down rate from physiological maturity to start of harvest is influenced primarily by weather factors and, to a lesser degree, by hybrid characteristics.  In simple terms, warmer temperatures and lower humidity encourage rapid field drying of corn grain.  Because moisture loss is greatest just after physiological maturity, both because the weather is usually warmer and because wet kernels lose water more easily, it stands to reason that a corn crop that matures earlier in the season will dry down faster than a crop that matures later in the season.

Updated from CropChatter post made in July 2015.

Farm Management Resources for Farmers – Manitoba Agriculture

Source: Manitoba Agriculture

With concerns over cash flow and market access for crop commodities, the Farm Management Team with Manitoba Agriculture have put together the following list of resources that could be used by producer applying for a cash advance or concerned/interested about financial management and risks.  The Farm Management Team focused on resources that could assist with increased loan exposure from a production / financial management / and risk management perspectives.

Contact information for Manitoba Agriculture’s Farm Management Specialists can be found here.

Manitoba Agriculture has many other resources available on their web pages here.

Financial Management

Production Economics

Business Risk Management

  • AgriInvest – helps cover small margin declines
  • AgriStability – assists in cases of large margin declines caused by circumstances such as low prices and rising input costs.

2019 Corn Field Tour – A Highlight on Research


A Highlight on Research funded by the MCGA.

The Corn Field Tour will make 3 field stops, covering several topics of interest.

12:00 PM: LUNCH – MCGA Bldg. 38-4th Avenue NE, Carman

1:00 PM: HAYWOOD – intersection of Highway 2 and Road 46 North. Turn West on Rd 46N, first field approach on North side of Rd 46N. Google Maps location link

4R Nitrogen on Corn – Dr. Mario Tenuta

Drone use, Green Seeker, Crop Circle sensors — Matt Gervais

2:30 PM: North of CARMAN – Krahn Agri Farms Ltd.

First Stop: 3 miles North of lights in Carman (Rd 37N, Albert School Rd), 3/4 mile West, North side. Google Maps location link.

Nitrogen Rate on Corn – Lanny Gardner

Row Spacing & Plant Populations – Dr. Yvonne Lawley

Second Stop: 2 miles North of lights in Carman (Rd 36N), 4.5 miles West, North Side.

MCGA On-Farm Test Nitrogen Timing

Farmer equipment on display

4:30 PM: North of ROLAND – 3 miles South of Carman (Rd 31N, Central School Rd.), 1/4 mile East, North side. Google Maps location link.

Strip Tillage in Corn

Fertilizer Placement in Strip Till Corn – Magda Rogalsky

Soil Warrior – Mike Eaton

Farmer equipment on display, 1 mile South

Register at

2019 Crop Diagnostic School

Attend the 2019 Crop Diagnostic School Hosted by Manitoba Agriculture & the University of Manitoba

The Crop Diagnostic School is designed to refine the diagnostic skills of agronomists and producers involved in field scouting and assessing crop health. This event is organized by Manitoba Agriculture and the University of Manitoba (U of M).

Daily sessions for the 2019 school will be held July 9 to 12 and July 16 to 18 at the Ian N. Morrison Research Farm (U of M Carman Research Facility), located 1.8 km west of Carman. 

**New for 2019**  A reduced rate for farmers of $50 per person, limited to 15 spots per day.
Please register early to ensure your booking. 

How to Register

Due to the hands-on training nature of this school, enrolment is limited to 75 people per day. To register or for more information, call the Crop Industry Branch at 204-745-5660 in Carman or email


Evaluation of Nitrogen Decision Guides for Fertilizing Corn in Manitoba (Completed 2016)

Manitoba Agriculture nitrogen rate guidelines for corn were developed before 1990 and are out-of-date for current yield levels. Recently NDSU has released N rate guidelines for corn and a number of in-crop scouting measures can be used to assess sufficiency and need for more N. A study was initiated to evaluate a number of N decision guides for suitability in fertilizing corn in Manitoba.  Read the 2016 results here.

4R Fertilizer Management Survey (Completed 2017)

The MCGA funded a 4R Fertilizer Management Survey looking specifically at corn production in Manitoba. Given the prospects for growth in corn production, and the unique aspects of fertilizer management for corn production in Manitoba, it is important to have a strong understanding of fertilizer practices of corn producers. In addition, as fertility management is a prime driver for agronomic outputs, as well as environmental impacts (greenhouse gas emissions, energy use, water quality and land use efficiency), it is essential that adequate data is made available.

View information compiled by Morgan Cott, MCGA Field Agronomist & John Heard, Crop Nutrition Specialist with Manitoba Agriculture: Fertilization Practices of Manitoba Corn Growers.

Manitoba Corn Development Program (Completed 2018)

Grain Innovation Hub: Manitoba Corn Development Program
MCGA funding of up to $372,900 + $1,165,000 by GF2 over 5 years

Under this program work in Ottawa by Dr. Lana Reid’s GF2 corn breeding project was validated and complimented by a lot of work done in Manitoba.  Projects include:

1) Corn Breeding Project – for screening of AAFC developed inbreds and test hybrid crosses at several locations in Manitoba, establishment of a Goss’s Wilt screening nursery where hybrids can be challenged with the disease and tested for resistance and where screening methods can be standardized.

2) Corn End Uses Project – Dr. Derek Brewin, (Department of Agribusiness and Agricultural Economics, University of Manitoba) and Masters student Sabrina Reza studied the implications of changing demand for corn in Manitoba see the article “Forecasting Corn Demand in Manitoba” September 2017 MCGA newsletter for more information.

3) Identification and characterization of the bacterial populations causing Goss’s wilt on Corn in Manitoba.  Dr. Fouad Daayf, (Department of Plant Sciences, University of Manitoba) students and research associates studied the genetics of the Manitoba populations of Goss’s bacterial wilt. They have identified the strain(s) and compared these with other known strains.  Strains were also used to challenge several AAFC inbreds and early hybrid lines to determine the genetics behind corn resistance to the disease. View poster presentation distribution and diversity of the Goss’s Wilt pathogen population here.

4) Corn Physiology for flooding survival –  Dr.Claudio Stasola, (Department of Plant Sciences, University of Manitoba) and students studied the way that plant phytoglobin  expression in corn affects a hybrids ability to withstand flooding and they have identified the mode of action in corn roots.  

Read the full report here.

Manitoba Corn Initiative – Corn Agronomy, Fertility, and Agrometeorology Project (Completed 2018)

Manitoba Corn Initiative – Corn Agronomy, Fertility, and Agrometeorology Project
MCGA funding up to $208,556 + GF2 funding $231,189 over 5 years

Dr. Yvonne Lawley coordinated a team of researchers (Dr. Don Flaten, Dr. Derek Brewin & Dr. Paul Bullock) and students from the University of Manitoba for the corn improvement program co-funded by the Canada-Manitoba Growing Forward 2 funds.  Four masters students graduated throughout the five-year project.  Their results have been published in our newsletters that were mailed directly to MCGA members, including the April/May 2017 MCGA newsletter includes masters grad Patrick Walther’s article “On-Farm Trial: Corn Residue Management for Soybean Production in Manitoba”, in several magazine and newspaper articles “Prairie corn: Agronomics and economicsin the September 2017 Issue of the Corn Guide and Country Guide and through the various Twilight Tours held at the University of Manitoba Research Farm in Carman, MB. 

Here are a few materials that were produced from work done by MCGA funded students under the supervision of Dr. Yvonne Lawley at the University of Manitoba, Disc tillage not the only answer to corn residue, Tillage tools for Corn Residue Management, Managing Phosphorus and Zinc in Corn, Canola before Corn Cropping sequence effects.

The full report can be read here.

Corn Population and Row Spacing

Corn Population and Row Spacing – 2018-2019
MCGA Funding $36,225 + WGRF $36,225 + Cap Ag Action MB $68,040
Dr. Yvonne Lawley, Department of Plant Science, University of Manitoba

Project objectives are to:

  • Create a yield-density model for corn in central Manitoba for common row spacings in Manitoba.
  • Quantify the impact of corn row spacing and population on corn dry down.
  • Identify a targeted range of plant populations to optimize future research integrating fertilizer rates.