The Slow Dry Down & Harvest of the 2016 Grain Corn Crop

Modified from a previous Crop Chatter post made November 18, 2014.

November is here and there remains grain corn to be harvested in some parts of Manitoba. In some cases, moisture contents are still higher than wanted or wet field conditions are hampering progress. But with winter approaching, many are opting to harvest under the less than ideal conditions.

What are normal dry down rates in corn? The best dry down rates are in September. Under good weather conditions from the mid to end of September, dry down rates can vary from 0.75 to 1.0% per day (can be greater in some cases when conditions are warm, sunny and dry, or zero on cool, rainy days!). Into early October, dry down ranges from 0.5% to 0.75% per day. In late October, dry down rate will decrease to less than 0.33% per day. And into November, dry down rate will further decrease to 0.15% per day to negligible amounts.

It is important to keep in mind that moisture loss for any particular day may be higher or lower depending on the temperature, relative humidity, sunshine, wind or rain conditions that day.

However, regardless of kernel moisture content in November, if left standing the crop can dry down throughout the winter months to moisture contents below 20%.

Potential Yield Loss.  If the crop remains out longer than anticipated and into the winter months, potential yield loss will depend on many factors, including stalk strength, ear drop, snow cover or wildlife damage. Ear drop will vary by hybrid and environmental conditions as well as the amount of grain on the ear (smaller ears should stay attached better than larger ears).  Stalk strength should also be considered when evaluating harvest timing (and this includes assessments of stalk rots). Compromised stalk strength could lead to increased stalk breakage, resulting in lost yield.

If winter conditions are cool with minimal snowfall, then corn will continue to dry and can be harvested throughout the winter.

If you do find yourself in the position of needing/wanting to overwinter your corn, please touch base with your local MASC agent.

Submitted by:  Pam de Rocquigny, Provincial Cereal Crops Specialist, Manitoba Agriculture

Manitoba Agriculture on Twitter: @MBGovAg
Manitoba Agriculture on YouTube: www.youtube.com/ManitobaAgriculture
Manitoba Agriculture website: www.manitoba.ca/agriculture

 

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Weather & Hybrid Characteristics – Their Roles in Grain Corn Dry Down

Updated from Crop Chatter Posts Made in 2012 and 2015

Grain corn in Manitoba is maturing quickly, and some of the earliest maturing fields have reached physiological maturity. Normal plant processes and weather conditions are the major influences on grain dry down, although hybrid characteristics can also play a role. As corn harvest approaches, a quick review of the facts concerning grain drydown might be helpful.

Grain drydown can be separated into two stages: the grain fill period and after physiological maturity.

Drydown During Grain Fill. The grain fill stages (R1 to R5) begins at flowering and is completed at physiological maturity. Grain filling is characterized by the rapid accumulation of dry matter in the kernel and the rapid movement of water out of the kernel.  Decreases in kernel moisture occur from a combination of actual water loss (evaporation) from the kernel surface and the accumulation of dry matter.  The corn plant uses “internal plumbing” to move water out of the kernel since water movement out of the kernel is regulated by how much dry matter is being forced into the kernel.  The corn plant is much more efficient in removing water from the kernel using its “internal plumbing” instead of physical evaporation through the kernel surface.

Drydown After Physiological Maturity. Physiological maturity (R6) occurs when kernel moisture is at approximately 30% (but can vary).  At this stage of growth, a layer of cells at the base of the kernel dies and turns black (hence black layer), the “internal plumbing” is therefore disconnected, and a barrier is formed between the kernel and the corn plant.  For this reason, post-maturity grain moisture loss occurs primarily by evaporative loss from the kernel itself. Research many years ago established that post-maturity moisture loss through the kernel connective tissues (placental tissues) back to the cob is essentially non-existent.

Role of Weather. As moisture loss after maturity is due to physical evaporation, field drying of mature corn grain is influenced primarily by weather factors, especially temperature and humidity.  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.  However, it is important to keep in mind that grain moisture loss for any particular day may be quite high or low depending on the exact temperature, humidity, sunshine, or rain conditions that day. It is not unheard of for grain moisture to decline more than one percentage point per day for a period of days when conditions are warm, sunny and dry. By the same token, there may be zero dry down on cool, rainy days.

Role of Hybrid Characteristics.  A number of hybrid characteristics can influence the rate of dry down, but to a lesser degree than weather. However, when weather conditions are not favorable for rapid grain dry down, hybrid characteristics that influence the rate of grain drying become more important.  The relative importance of each trait varies throughout the duration of the field dry down process and, as mentioned earlier, is most influential when weather conditions are not conducive for rapid grain drying.

  • Husk Leaf Number. The fewer the number of husk leaves, the more rapid the grain moisture loss.
  • Husk Leaf Thickness. The thinner the husk leaves, the more rapid the grain moisture loss.
  • Husk Leaf Senescence. The sooner the husk leaves senesce (die), the more rapid the grain moisture loss.
  • Husk Coverage of the Ear. The less the husk covers the tip of the ear, the more rapid the grain moisture loss.
  • Husk Tightness. The looser the husk covers the ear, the more rapid the grain moisture loss.
  • Ear Declination. The sooner the ears drop from an upright position to a downward position, the more rapid the grain moisture loss.
  • Cob Diameter. The narrower the cob diameter, the more rapid the grain moisture loss.
  • Kernel Type.  Flint-dent kernel types tend to dry down slower in comparison to dent kernel types due to the harder nature of the kernel.

Submitted by:  Pam de Rocquigny, Provincial Cereal Crops Specialist, Manitoba Agriculture

Manitoba Agriculture on Twitter: @MBGovAg
Manitoba Agriculture on YouTube: www.youtube.com/ManitobaAgriculture
Manitoba Agriculture website: www.manitoba.ca/agriculture
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Frost Prior to Physiological Maturity in Corn

When frost occurs in the early fall before corn has reached physiological maturity (black layer), there is always concern about impact to yields and quality. The stage of crop, minimum temperature reached, relative humidity and duration of cool temperatures all contribute to the impact frost will have on the crop. Generally speaking, a light frost is considered below 0 but above -2°C, where a heavy frost is -2°C and greater.

In corn, grain yield and quality losses become less of a concern the closer the corn is to physiological maturity.

At R5, or the dent stage, crop impacted by either a light or heavy frost will be harvestable but there will be an impact to yield and quality (see Table 1). Within R5, kernels are often staged according to the progression of the milk line, i.e. ¼, ½, ¾. At ½ milk line (R5.5), moisture content of kernels is 35-40% and days to maturity is approximately 13-18 days away.

The stage R6, or physiological maturity, is reached when the milk line disappears and the starch line has reached the base of the kernel. Kernels have reached maximum dry matter accumulation and kernel moisture can range between 30 to 35% (but does vary by hybrid and environment). The formation of the black layer serves as a visual cue that the plant is mature.  At this stage, frost will have minimal impact to yield or quality.

Table 1: Relationship between corn growth stages and calendar days to maturity, yield loss, and other kernel characteristics

Days to Maturity Grain Corn

Source: NDSU Crop & Pest Report – August 8, 2013

A killing frost (-2°C) any time prior to physiological maturity (R6) will kill the entire plant which will stop kernel development. However, if the frost is not a killing frost and the leaves/stalks and husks are still green afterwards, grain filling will continue until maturity.

Picture2

Frost symptoms are water soaked leaves that eventually turn brown. Because it is difficult to distinguish living from dead tissue immediately after a frost event, the assessment should be delayed for a few days after a frost. (Photo by P. de Rocquigny)

Even though the leaves may be impacted, the plants will continue to scavenge nutrients from the remaining plant material to help complete growth and maturity.  However, the crop will still need the necessary heat units to aid in maturity.  If the necessary heat units aren’t received, a premature black layer may form, ending further grain fill, potentially impacting yield but more likely quality.

Submitted by: Pam de Rocquigny, Provincial Cereal Crops Specialist, Manitoba Agriculture

Manitoba Agriculture on Twitter: @MBGovAg
Manitoba Agriculture on YouTube: www.youtube.com/ManitobaAgriculture
Manitoba Agriculture website: www.manitoba.ca/agriculture

 

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Historically, what has been seeding progress prior to May 1st?

Some producers have started their 2016 seeding operations, with spring wheat being seeded and from what I’ve heard a few acres of corn as well.  With some seeding done, I’ve been asked the question: “What has been seeding progress prior to May 1st in Manitoba in recent years?”.

Producers who participate in AgriInsurance provides seeding date information to Manitoba Agricultural Services Corporation (MASC).  This dataset provides us a historical perspective of when seeding has taken place in the past.

In Table 1, cumulative seeding progress prior to May 1st for six crop types is provided.  A five year (2010-2014) average cumulative seeding progress is noted, along with what was seeded prior to May 1st in 2015. Please note that data is for final insured crop in the ground.

Table 1:  Seeding progress in Manitoba prior to May 1st.

Historical Planting Progress prior to May 1st

Data Source:  Manitoba Agricultural Services Corporation (MASC)

What the table doesn’t show is the wide range of seeding progress prior to May 1st over the past few years.  If we look at seeding progress for red spring wheat in Manitoba, we’ve seen less than 1% of acres seeded prior to May 1st (2009, 2011, 2013 and 2014) but as many as 65% of acres (2010) planted in April.

Look for future updates to historical seeding progress as we enter May!

Submitted by:  Pam de Rocquigny, Provincial Cereal Crops Specialist, Manitoba Agriculture

Follow Manitoba Agriculture on Twitter (@MBGovAg) to receive updates on seeding progress through the weekly Manitoba Crop Report.
The weekly crop report is also available at Manitoba Crop Report.

 

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2015 Corn Hybrid Performance Results Now Available!

The Manitoba Corn Committee’s 2015 Corn Hybrid Performance Trial brochure is now available on the Manitoba Corn Growers Association website at http://manitobacorn.ca/manitoba-corn-committee/.  It contains data on grain corn hybrid performance at 3 locations and silage corn hybrid performance at 2 locations. You can download the entire report or by the individual locations.

Morgan Cott, Field Agronomist with the Manitoba Corn Growers Association, has pulled together the brochure.

Happy Reading!

Submitted by:  Pam de Rocquigny, Provincial Cereal Crops Specialist, MAFRD

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Estimating Date of Grain Corn Maturity from Silking Stage

The 2015 season has seen relatively normal accumulation of corn heat units (CHU), with a range of 92% of normal to upwards of 111% of normal as of July 19th. According to Issue #12 of the Manitoba Crop Report, grain corn ranges in development from late vegetative stages to silking (R1).

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 Hybrid Approximate CHU Required from Silking to Physiological Maturity
2100 945 to 1050
2200 990 to 1100
2300 1035 to 1150
2400 1080 to 1200
2500 1125 to 1250
2600 1170 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
Brandon 31-Aug 07-Sep 14-Sep 25-Sep 10-Oct
Elm Creek 28-Aug 03-Sep 09-Sep 17-Sep 27-Sep
Emerson 26-Aug 31-Aug 06-Sep 12-Sep 19-Sep
Morden 26-Aug 30-Aug 05-Sep 10-Sep 17-Sep
Portage 28-Aug 03-Sep 09-Sep 17-Sep 28-Sep
Selkirk 26-Aug 31-Aug 06-Sep 12-Sep 21-Sep
Starbuck 29-Aug 04-Sep 10-Sep 17-Sep 28-Sep
Steinbach 28-Aug 03-Sep 09-Sep 16-Sep 26-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
Brandon 12-Sep 22-Sep 05-Oct 01-Oct
Elm Creek 08-Sep 15-Sep 25-Sep 08-Oct
Emerson 05-Sep 11-Sep 18-Sep 28-Sep 12-Oct
Morden 04-Sep 10-Sep 17-Sep 26-Sep 09-Oct
Portage 08-Sep 16-Sep 26-Sep 12-Oct
Selkirk 05-Sep 12-Sep 20-Sep 01-Oct 24-Oct
Starbuck 08-Sep 16-Sep 25-Sep 09-Oct
Steinbach 08-Sep 15-Sep 24-Sep 08-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.

Submitted by:  Pam de Rocquigny, Provincial Cereal Crops Specialist, MAFRD

For more information on corn production, please visit MAFRD’s webpage at http://www.gov.mb.ca/agriculture/crops/production/grain-corn/index.html
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Yields Respectable in 2014 Despite a Challenging Year

Manitoba Agricultural Services Corporation (MASC) has released an early version of the 2014 yield report with 99.8% of the Harvest Production Reports (HPRs) keyed in.  The table below summarizes the 2014 average yield by crop type based on the harvested acres, as well as comparisons to 2013 and a 5-year average (2009 to 2013).

2014 yields

In February 2015, MASC will release their annual Yield Manitoba publication and update their Manitoba Management Plus Program (MMPP) website (http://www.mmpp.com/mmpp.nsf/mmpp_index.html) where further information on yields and acres by variety will be released.  Additionally, the data will be more complete in February as all HPR’s will be keyed in.

Submitted by:  Pam de Rocquigny, Anastasia Kubinec & Dennis Lange, Crop Specialist with MAFRD

Special Thanks to Doug Wilcox, MASC, for providing the 2014 data!

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Goss’s Wilt in Corn: 2014 Manitoba Disease Survey

Goss’s Wilt of corn is caused by the bacterium Clavibacter michiganensis subsp. nebraskensis, and has been present in Manitoba since it was originally identified near Roland in 2009.

In 2014, 74 corn fields were surveyed across the major grain corn growing areas of the province. The disease was detected in 14% of the fields randomly surveyed.  Goss’s Wilt was detected in the rural municipalities (RM) of Roland, Thompson, Dufferin, Montcalm, Morris and Portage la Prairie.  In addition, the disease was observed in the RM’s of Stanley and Rhineland, although not in the fields that were part of the survey. In past years, Goss’s Wilt has also been detected in the RM of Hanover.

Figure 1: Goss’s Wilt provincial survey results where red crosses indicate fields where disease was found and green dots indicate fields where disease was not detected.

Goss's Wilt survey map

Results indicate that Goss’s Wilt has spread to most of the grain corn growing areas of Manitoba, and therefore, is something  that must be scouted for and managed by all growers.

For more information on disease symptoms of Goss’s Wilt, life cycle of the disease, management options and complete methodology and results of the 2014 survey, please view the attached poster which was presented at the 2014 Manitoba Agronomists Conference:

Goss’s Wilt in Corn: 2014 Manitoba Disease Survey (Holly Derksen, MAFRD & Morgan Cott, MCGA)

Submitted by: Holly Derksen, Field Crops Pathologist, MAFRD

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2014 Corn Hybrid Performance Results Available

The Manitoba Corn Committee’s 2014 Corn Hybrid Performance Trial brochure is now available on the Manitoba Corn Growers Association website at http://manitobacorn.ca/manitoba-corn-committee/.

Morgan Cott, Field Agronomist with the Manitoba Corn Growers Association, has pulled together the brochure.  Please take some time to read the “Welcome to the 2014 Brochure” article by Morgan as it contains important information on the 2014 growing season.

Happy Reading!

Submitted by:  Pam de Rocquigny, Provincial Cereal Crops Specialist, MAFRD

 

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Should I apply fungicide after a hail event?

Originally Published August 19, 2014

A fungicide application cannot recover yield potential lost due to hail damage. Fungicides protect yield potential by reducing disease.  Many studies have been conducted in the United States looking at fungicide application to hail damaged corn crops.  Most results show no yield response when a fungicide has been applied to hail damaged corn.  If after the hail event, conditions are conducive for fungal disease development, an application of fungicide may provide yield protection.  But again it won’t recover the yield lost due to the hail event.

Also keep in mind that bacterial diseases, such as Goss’s Wilt that infect plants through wounds, are not controlled by fungicide application.  And many diseases do not require a wound to infect the plant, including common smut and stalk rots.  Furthermore, foliar diseases that can be managed with foliar fungicides, such as gray leaf spot, do not need wounds for infection.

Bottom line is disease pressure plays a critical role in the magnitude and consistency of a yield response to a foliar fungicide application in corn.  So instead of basing a fungicide application on the fact that it hailed, it should instead take into account disease risk factors such as:

  • Susceptibility of the corn hybrid to various diseases that would be controlled by a fungicide application.
  • Previous crop as many foliar pathogens can survive on corn residue.
  • Weather since the risk for disease development will increase in rainy and/or humid weather.

If you do choose to apply a fungicide to hail damaged crops this year, it would be a good idea to conduct a replicated on-farm trial in the field to allow for a comparison of treatment effectiveness at the end of the growing season.

Submitted by: Pam de Rocquigny, Provincial Cereal Crops Specialist, Manitoba Agriculture

 

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