Agronomy & Extension – Special Crops Archives - Page 3 of 4

Funding to support sustainable practices available to Manitoba farmers

mca2022dev on May 26, 2023

The Agricultural Climate Solutions – On-Farm Climate Action Fund (OFCAF) was established to provide funding and support to farmers in adopting practices that store carbon and reduce greenhouse gas emissions. In Manitoba, funds are available through the Manitoba Association of Watersheds and the Canola Council of Canada. Farmers may only receive funding from one organization for a given eligible beneficial management practice on a given parcel of land. More information on these programs, including a summary of eligibility criteria and beneficial management practices can be found here.

The Sustainable Canadian Agricultural Partnership (SCAP) – Sustainable Agriculture Manitoba

The Sustainable Canadian Agricultural Partnership (SCAP) is an investment by the federal, provincial and territorial governments to support the agriculture, agri-food and agri-based products sector. As part of the SCAP, the Manitoba government has now opened intake for the Sustainable Agriculture Manitoba (SAM) program, which provides funding to farmers to support the implementation of beneficial management practices that increase the environmental and economic sustainability of agriculture operations in Manitoba. Funding streams that may be of particular interest to MCA farmer members include:

Crop Land Management: Funding to support adoption of cropland management practices that optimize operations and improve productivity. Eligible beneficial management practices include:

Reduced Tillage Intensity
Low Disturbance Placement of Seed & Fertilizer
Preventing Soil Compaction
Reduced Pesticide Use
Soil Landscape Restoration
Perennial Cover for Sensitive Lands
Hazardous Products Storage

More information on the Crop Land Management funding stream is available here.

Water Management: Funding to support the adoption of practices that enhance the supply, efficient use, quality and management of water. Eligible beneficial management practices include:

Increased Irrigation Efficiency
Fertigation
Sub-surface Drainage Water Management
Water Quality
Runoff Control
Water Use Efficiency
Water Supply

More information on the Water Management funding stream is available here.

To be eligible for funding through the SAM program, farms are required to have a valid Environmental Farm Plan (EFP). Information on Manitoba’s EFP can be found here.

Application intake for the SAM program closes at 11:59 pm on Tuesday June 13, 2023. For more information on this program and other SCAP programs you may be eligible for, visit the link below.

https://www.manitoba.ca/scap/index.html

Availability of Lambda-Cyhalothrin Insecticide and How It Affects Sunflowers

mca2022dev on February 28, 2023

By Manitoba Crop Alliance

Many major lambda-cyhalothrin products have been made unavailable to Canadian farmers for 2023 due to a label revision. This revision has a significant focus on feed-related commodities, which affects most Canadian commodities, but also includes concerns to human health and safety via consumption.

In sunflowers, Manitobans only had access to one insecticide (Matador) to control lygus bug, which is a significant pest in confection sunflowers due to their ability to negatively affect quality. Matador is now removed from our repertoire, leaving no current chemical options to control lygus bugs in sunflowers. Manitoba Crop Alliance and Manitoba Agriculture are working with industry to determine if an Emergency Use Registration will be possible for the 2023 growing season with any current products that have lygus bug on label but are not registered for use on sunflowers. It is a common occurrence in minor crops to not be included on label, so in these instances it requires a label expansion, which is an extensive process.

Lygus bugs are a major pest of sunflowers because they can cause kernel brown spot, which is a small brown to black spot on the blunt end of the seed. The industry standard allows for a maximum of 0.5% kernel brown spot in confection sunflowers marketed for human consumption. The economic threshold for lygus but in confection sunflowers is one bug per 9 sunflower heads. Each adult lygus bug is capable of damaging as many as 35 seeds per head.

Control of lygus bug is very limited and insecticides (lambda-cyhalothrin) are the most effective option in sunflowers. Cultural options are even more limited. When planning sunflower acres, it is recommended to avoid planting near adjacent canola fields since they are both favourable host crops to lygus bug. Canola does have limited insecticide options available for lygus bug, so in canola-lygus infestation and insecticide application scenarios, those neighbouring lygus bugs will attempt to move out and find another host crop, like sunflowers.

Some environmental and biological control factors from Manitoba Agriculture include:

Weather: Heavy rainfall may reduce levels of early-instar nymphs of lygus bugs. A study in alfalfa found heavy rainfall reduced first generation nymphs of Lygus lineolaris by 50%.

Biological Control: Nymphs of Lygus bugs may be killed by parasitic wasps in the genus Peristenus (Hymenoptera: Braconidae); with parasitism being common in weedy alfalfa stands or uncultivated weedy sites but very low in canola. Damsel bugs, assassin bugs, lacewing larvae, big-eyed bugs and crab spiders can prey on lygus bugs. Protecting these natural enemies by avoiding unnecessary insecticide applications may also help to reduce the impact of lygus bugs.

Manitoba Crop Alliance and Manitoba Agriculture will update farmers and industry of any changes in the insecticide market that affects lygus bug control in sunflowers in the near future.

Tips and Tricks for Sunflower Harvest

mca2022dev on October 6, 2022

MOISTURE TESTING SUNFLOWER SEED >15% MOISTURE

The following procedure is suggested for testing the moisture content of high moisture sunflower with the microwave oven.

Harvest seed samples from different parts of the field and mix all samples together. Separate this total sample into at least four 50 gram samples for the tests. Make sure the samples are clean and hand pick out foreign material if necessary.
Weigh a paper towel using a gram scale and record the weight. With the towel on the scale, pour a sample of seeds onto the scale and record that weight.
Place the towel and seeds into the microwave oven; spread the seeds on the towel to a thickness of no more than about two seeds.
Microwave for four-minute intervals; take out the sample and weigh it after each period. When the difference in weights become small, start weighing at two-minute intervals until there is no weight change. Lack of weight change indicates that the moisture has been removed.
If running repeated samples for a long time, check to see if the glass tray in the oven is getting hot. If so, let the tray cool before running another test. If a sample starts to smoke or appears charred after a test, discard this sample and start another test after the oven and tray cool.
Calculate the original seed moisture content of the sample by using the following equation. Be sure to subtract the weight of the paper towel from the initial and final sample weights before you begin the calculations.

Moisture content = (Initial weight – Final weight) / (Initial weight) x 100.

Be sure to run a minimum of four tests and average the results.
Do not leave the microwave oven unattended during the tests.

Confection sunflower should be under 10% moisture (between 9% and 10% is best) for proper storage. Oil sunflower moisture content should be 10% or less for winter storage and 8% or less for storage during warmer months.

Getting there can be a balancing act at harvest: Wait too long for natural dry down, and sunflower standing in the field can become too dry and vulnerable to quality deterioration and shelling out. Cut too early and there’s greater chance for deterioration during storage if seed moisture is too high. Many experts advise combining ‘flowers at 12-15% moisture and using natural air drying to get stored see moisture under 10%.

HARVESTING HIGH MOISTURE SUNFLOWERS

Sunflowers can be combined when the seed moisture is below 20 percent. Harvesting when seed moisture is greater than 20 percent can result in scuffing during harvesting and shrinkage during drying. It would be preferable to combine seeds at 10 to 13 percent moisture.

Scuffing is caused when sunflowers are harvested at a high moisture content. The combine causes mechanical damage by peeling away part or all of the top layer of the shell, giving the seed the appearance of sclerotinia damage or white seeds. Processors are known to discount for scuffing, even though it leaves no impact on the product itself.

HINTS & REMINDERS FOR HARVESTING SUNFLOWERS (Special Bulletin – Harvest)

Combine headers: Platform (wheat), row-crop, and corn headers have all been used successfully with sunflower. Row-crop heads are perhaps the best choice because they can be used without modification. Corn heads need to be modified with a stationary cutting knife before use with sunflower. Combines used for threshing small grains can be adapted to harvest sunflower with a variety of header attachments available with many operating on a head stripper principle.

Have the header platform raised high enough to take in the heads, minimizing stalks as much as possible. The overall goal of the threshing process should be passing the head nearly intact through the combine, or in a few large pieces, with all developed seed removed from the head. If the head is being ground up into small pieces, there will be excessive trash in the grain. Platform heads can be used without modification, but often have a higher amount of seed and head loss than a row head. Adding pans to the front of the platform, and/or modifying the reel can improve efficiency. Twelve-inch pans are best for 30-inch row spacings; 9-inch better for other row sizes and solid seeding.

Common threshing mistake: Waiting to harvest and seeds become too dry and shell out. Better: combine at 14-15% moisture and use air/dry down to under 10% moisture. Waiting too long to harvest can result in excessive field losses.

Threshing goal: Have the header platform raised high enough to take in the heads, minimizing stalks as much as possible. The overall goal of the threshing process should be passing the head nearly intact through the combine, or in a few large pieces, with all developed seed removed from the head. If the head is being ground up into small pieces, there will be excessive trash in the grain.

Fan speed: Air speed should be lower, due to the lighter weight of sunflowers (oils weigh about 28 to 32 lbs/bu, confection 22 to 26 lbs/bu). Excessive wind may blow seed over the chaffer and sieve, and seed forced over the sieve and into the tailings auger will be returned to the cylinder and may be dehulled. Set the fan so only enough air flow is created to keep trash floating across the screen/sieve. The concave should generally be run wide open (on a rotary combine, a rotor-to-concave setting of 3/4 to 1 inch is appropriate). A bottom screen or lower sieve of 3/8 inch, and a top screen/upper sieve of 1/2 to 5/8 inch is typical.

Forward speed: Combine forward speed should usually average between 3 and 5 miles per hour. Forward speed should be decreased as moisture content of the seed decreases to reduce shatter loss as heads feed into the combine. Faster forward speeds are possible with seed moisture between 12 and 15%.

Cylinder/rotor speed: Slow cylinder/rotor speed to 250 to 400 rpm. Normal cylinder speed should be almost 300 rpm (for a combine with a 22” diameter cylinder to give a cylinder bar travel speed of 1,725 feet per minute). Speed will vary depending upon crop conditions and combine used. Combines with smaller cylinders will require a faster speed and combines with a larger cylinder diameter will require a slower speed. A rotary combine with a 30”cylinder will need to be operated at 220 rpm, and a combine with a 17” cylinder will need to be operated at 390 to have a cylinder bar speed of 1,725 feet per minute. If a combine cylinder operates at speeds of 400 to 500 rpm, giving a cylinder bar speed of over 2,500 feet per minute, very little seed should be cracked or broken if the moisture content of the seed is above 11%. Cylinder bar speeds of over 3,000 feet per minute should not be used because they will cause excessive broken seed and increased dockage.

Concave clearance: When crop moisture is at 10% or less, conventional machines should be set open to give a cylinder to concave spacing of about 1″ at the front of the cylinder and about 0.75″ at the rear. A smaller concave clearance should be used only if some seed is left in the heads after passing through the cylinder. If seed moisture exceeds 15 to 20%, a higher cylinder speed and a closer concave setting may be necessary, even though foreign material in the seed may increase. Seed breakage and dehulling may be a problem with close concave settings. Make initial adjustments as recommended in the operator’s manual. Final adjustments should be made based on crop conditions.

Harvest Loss Rule of Thumb: Ten seeds per square foot (don’t forget heads that have seed left in them) represent a loss of 100 pounds per acre, assuming seed loss is uniform over the entire field. Harvest without some seed loss is almost impossible. Usually, a permissible loss is about 3%. Loss as high as 15 to 20% has occurred with a well-adjusted combine if the ground speed is too fast, resulting in machine overload.

Are your bins ready? Bins with perforated floors work better for drying sunflower than those with ducts. Aeration is essential, especially in larger bins. Aeration may be accomplished with floor-mounted ducts or portable aerators. Aeration fans should deliver 1/10 to 1 cfm per cwt of sunflower. If aeration is not available, sunflower should be rotated between bins to avoid hot spots developing in the stored grain.

Cleaning before storage: When excessive trash is present in the harvested grain, cleaning before storage can greatly reduce incidence of storage problems. Ambient air can be used to cool and dry sunflower. If heated air is used, generally a 10 degree F increase in temperature over ambient is sufficient to increase rate of drying. Be aware that sunflower dries more rapidly than corn or soybeans, and should be monitored to avoid over-drying.

Watch for Moisture Rebound: When tracking moisture readings on sunflower seeds that are being dried in a bun, keep in mind that the hull dries faster than the kernel. Thus, a moisture reading taken on sunflower being dried may be artificially low; for example, a moisture meter may give a reading of 10%, and then climb back up to 12% the next day. To get a more accurate reading, place some seed in a covered jar overnight and take moisture readings the next day, after the hull and kernel moisture have equalized.

Prepare for Fire Hazards: Always keep in mind that sunflower is an oil-based crop and fine fibers from sunflower seeds pose a constant fire hazard, especially when conditions are dry. Keep your combine and grain dryer free of chaff and dust (consider having a portable leaf blower on hand for this). Keep a small pressure sprayer or container filled with water on hand in the combine in case of fire. Should the threat of extreme dry conditions and combine fires persists; try nighttime harvesting when humidity levels are higher.

Estimating Yield in Grain Corn

mca2022dev on October 5, 2022

Estimating grain corn yield in any given field is exactly that – an estimate. The more samples and counts that are taken, the better variations in the field will be captured and accounted for. However, on that same note, no matter how many counts are done in a field, a variance of 20 bushels of yield (plus or minus) is a reasonable expectation.

A STEP-BY-STEP PROCESS FOR GRAIN CORN YIELD ESTIMATION:

1. Prior to sampling, determine how many samples or counts will be taken in each field. A minimum of 5 is recommended, 5 – 10 being appropriate. Of course, the more counts that are taken, the better representation of the field, overall.

Tools needed: measuring tape, pen and paper. A calculator can be used in the field, or once all samples are completed, but will be required.

2. Enter the field and walk in several paces beyond the headlands. Pick a representative location to take the first count.

3. Measure a single row to the appropriate length of 1/1,000^th of an acre. For the most common 30” row spacing, 17’5” is the appropriate length.

Figure 1: Row length required to measure 1/1,000^th acre in various row widths

4. In the chosen 1/1,000^th acre, count and record the number of harvestable ears on the plants. Do not count ears that have either dropped or may be on lodged plants and will not be picked up by the combine header.

5. Choose every 5^th – 6^th ear in the row and record the number of kernel rows and average kernels per row, and multiply the two factors for each chosen ear.

Be sure to be selecting representative ears.
Kernel rows are typically 12 – 18, but can be fewer or greater than that.
Kernels per row – do not count aborted kernels; do not count the extreme base or tip kernels.

6. Add all counts together for the first site, then divide by number of sampled ears. For example, if 5 ears were sampled with kernel counts of 336, 384, 512, 496 and 600, the average number of kernels per ear: (350 + 380 + 510 + 500 + 625)/5 = 473

7. Yield for each sample site in one field is determined by multiplying ear number (Step 4) by the average number of kernels per ear (Step 6) and then dividing that total by 90. 90 represents the average number of kernels in a bushel of corn at 15.5% moisture (90,000). In a scenario where grain fill has exceptionally good, decrease that value to 80, and conversely, increase that number to 100 if grain fill has been particularly stressful and grain is lightweight.

Figure 2: Grain corn yield estimate formula – Iowa State University (https://crops.extension.iastate.edu/cropnews/2017/08/estimating-corn-yields-using-yield-components)

Formula example for sample site #1:

Let’s say 31 harvestable ears were counted at the first sample site.

(31 harvestable ears * 473 kernels per ear)/90 = 163 bushels per acre for average/normal grain fill.
(31 harvestable ears * 473 kernels per ear)/80 = 183 bushels per acre for exceptional grain fill.
(31 harvestable ears * 473 kernels per ear)/100 = 147 bushels per acre for a below average grain fill.

Repeat this procedure 5 – 10 times throughout the field to get a good representative estimate and average the number of sites to yield calculations. Let’s say 7 sample sites were calculated:

(163 bu. + 182 bu. + 155 bu. + 159 bu. + 171 bu. + 176 bu. + 164 bu.)/ 7 sample sites = 167 bu/acre yield estimate for this grain corn field sampled.

REFERENCES:

Estimating Corn Grain Yield Prior to Harvest

Estimating Grain Corn Yield

Estimating Corn Yields Using Yield Components

Common Preharvest Questions in Flax

mca2022dev on September 9, 2022

What is the staging for a preharvest or desiccation in flax?

Flax is considered physiologically mature when 75% of the bolls (in the field or on a plant) are brown and the boll segments have begun to separate. This is a visual rating that corresponds to a grain moisture content of around 30% and is known as the 75% boll turn or 75% brown boll stage.

Figure 1: Flax Maturity Ratings. Credit: SaskFlax

What is the difference between a preharvest aid and a desiccant?

Two types of chemicals are available to assist with flax harvest management: pre-harvest herbicides (sometimes called harvest-aids) and desiccants.

Pre-harvest herbicides are non-selective systemic herbicides that provide late season perennial weed control and may improve the harvestability of the crop by reducing the amount of green material in the field.
Desiccants are non-selective herbicides that rapidly dry down the crop and weeds to allow for an earlier harvest.

Figure 2: Comparison between preharvest herbicide and desiccant characteristics. Credit: SaskFlax

Can we use glyphosate as a preharvest aid?

Since it does terminate the crop, preharvest glyphosate may assist with stem dry-down and harvestability, however it is expected that the effects of glyphosate applied alone on flax dry-down can be slow and potentially inconsistent depending on environmental conditions. This all being said, at this time, it is not a recommendation of Manitoba Crop Alliance to apply glyphosate as a preharvest aid due to inconsistent results with maximum residue limit (MRL) testing. If a producer must use glyphosate, it is strongly recommended to speak with their grain buyer to determine if a glyphosate application to their flax will be a marketing concern.

What are the current registered preharvest aids and desiccants for flax in Manitoba?

Figure 3: Preharvest chemicals registered for use on flax. Credit: SaskFlax

References:

SaskFlax: Preparing for Harvest, July 2018. https://www.saskflax.com/quadrant/media/Pdfs/Flax%20on%20the%20Farm/180724_July_Flax_on_the_Farm_Final.pdf

Indian Head Agricultural Research Foundation: Pre-harvest Weed Control and Desiccation Options for Flax, 2019. https://iharf.ca/wp-content/uploads/2021/04/Pre-harvest-weed-control-and-desiccation-options-for-flax.pdf

SaskFlax: Flax Markets and Maximum Residue Limits, April 2022. https://www.saskflax.com/quadrant/media/Pdfs/Flax%20on%20the%20Farm/2022/220425%20MRL%20Information-April.pdf

Article written by Morgan Cott, Agronomy Extension Specialist – Special Crops with Manitoba Crop Alliance

Head Rot Identification in Sunflowers & Harvest Management

mca2022dev on September 8, 2022

Rhizopus Head Rot

Rhizopus rarely occurs in Manitoba and is more of a southerly disease, however it is possible to see it here after severe storms and hail, followed by very high heat. Identifying factors that separate Rhizopus from other head rots are gray mycelia with very small black structures.

Rhizopus begins as a typical “water-soaked” dark spot on the back of a sunflower head that grows into a larger watery, soft rot and then dries and turns darker brown. Eventually, heads dry down, though this occurs prematurely in comparison to healthy plants, and infected tissue shreds, exposing gray threadlike strands of mycelial growth.

Key points:

Enters head via wound caused by hail, most commonly
Water-soaked lesion on backs of sunflower head
Gray mycelial growth inside the diseased head, which can later present itself on the face of the sunflower head
Tiny black spots, about the size of a pinhead
100% yield loss potential due to dropped heads

Figure 1: Dry and skeletonized head (Bob Harveson, University of Nebraska)

Figure 2: Coarse, dirty white to gray, threadlike fungal growth of Rhizopus spp. in sunflower head (Bob Harveson, University of Nebraska)

Sclerotinia Head Rot

Sclerotinia is very common in Manitoba and in several grain crops, which makes crop rotation the best management practice for this prevalent disease. A recommendation for sunflowers is to only include it in rotation when other sclerotinia host crops have not been grown on that field for 4-7 years. Chemical control is used frequently, however due to the small window for application, coverage is difficult to rely on.

Sclerotinia presence can first be found in the field by identifying cup-shaped apothecia growing on the soil surface, which produce ascospores. Symptoms in the field include the typical tan-coloured lesions on the back of sunflower heads that may be soft to the touch. As the infection spreads, the head becomes pliable and easily torn open to reveal black sclerotia bodies amongst white mycelia. Fronts of sunflower heads may have white mycelial growth, or mould, visible between the seeds. Eventually, heads will likely shred and disintegrate leaving frayed vascular elements that appear broom-like.

Key points:

Cup-shaped apothecia on the soil
Water-soaked lesions on backs of sunflower head
Black sclerotia bodies inside sunflower head following disease progression
White mycelial growth between and on seeds
Shredding sunflower head, resembling a straw broom

Figure 3: Sclerotinia Head Rot on Sunflower

Figure 4: Sclerotinia Head Rot Symptoms in Sunflower

Figure 5: Sclerotinia Disease Cycle, American Phytopathological Society

HARVEST MANAGEMENT IN DISEASED SUNFLOWERS

Yield loss from sclerotinia head rot in sunflowers is a result of empty seeds, rather than poor quality. In fact, it is not uncommon to find large sclerotia bodies being harvested along with seed and degrading quality in that manner.

Due to the overall degradation of disease plants, not just from sclerotinia, it is a good practice to harvest infected fields first. The diseased areas should dry down more rapidly than healthy plants and standability isn’t reliable, whether that is a result of a stalk rot or head rot. The physical breaking of stalks or dropping of heads leads directly to yield loss due to the inability to pick up the grain with a header.

Article written by Morgan Cott, Agronomy Extension Specialist – Special Crops with Manitoba Crop Alliance

Late Season Planting

mca2022dev on June 3, 2022

The reality of seeding or planting any crop into June is that yield penalties will occur. This could be due to reduced bushel weight, small seed size, and low quality grain as a result of early fall frost or poor environmental conditions leading up to maturity.

Planting corn or sunflowers beyond May 30^th is still a possibility in 2022, but hybrid selection is of utmost importance, since we have already missed out on 250 crop heat units or more, depending on location. Sunflowers require 115 – 130 days to mature in Manitoba, with the varieties we currently have available. So, a sunflower crop that is planted on June 1^st, will mature by September 24^th, at the earliest.

Sunflowers are a great option in a wet year, if you can get them planted. They are one of the top water-users that we grow in Manitoba, only behind corn and roughly tied with soybeans. They are very well adapted to dry growing seasons as well because they will search much further for water sources than other crops.

The following tables are taken directly from a NDSU Extension article, “Replanting or Late Planting Crops”: https://www.ndsu.edu/agriculture/ag-hub/publications/replanting-or-late-planting-crops. Note that the majority of North Dakota accumulates several more crop heat units than Manitoba, even at our most southern locations, but these tables do depict a good indication of what a farmer is looking at for yield loss when planting into June.

https://www.ndsu.edu/agriculture/ag-hub/publications/replanting-or-late-planting-crops

The data provided here is very cautious and simply states that anything grown after May has very little chance of being economical, which isn’t completely true, but it does encourage the fact that a farmer does have to be wary of what is being seeded after that point. The risks involved are obvious and great care must be taken in order to get any late seeded or planted crop to germinate as quickly as possible and off to a healthy start. It is not unheard of to have a crop emerge within just a few short days of planting when soils are warm and have good moisture, and the quicker that crop gets growing, the more water it will start using. Take great care in placing seed accurately in the soil, control weeds and fertilize accordingly to mitigate any early season stresses.

Corn Ear Drop

mca2022dev on September 27, 2021

Drought conditions affect a corn crop in many different ways throughout the growing season. Silking and pollination stages are very sensitive to hot, dry conditions. Not only does the lack of rain and extreme temperature cause silks to dry up, poor pollination, and aborted kernels, but these conditions can also interfere with ear shank development.

In drought stress situations, the grain will “steal” carbohydrates from the rest of the plant, including the ear shank, in order to fill and improve quality. As result, the ear shank may become weak and eventually be unable to hang onto the ear as it becomes heavier. Another possible culprit for weakened ear shanks is in a year with rapid drydown in late summer. The cells that connect the ear shank to the ear dry too quickly and become brittle and unable to hold that ear tightly anymore. A disturbance to the corn plant, eg. a silager or combine header, can shake the ear from the plant which results in a complete yield loss for that plant.

Stalk diseases are not common in a drought year, however they are still possible. Stalk rots, such as Fusarium, will weaken the corn stalk and also the ear shank, potentially causing ear drop. Insects like European corn borer will also burrow throughout a corn plant, like in the stalk, ear shank and even the ear, which will weaken those areas of the plant.

This is generally not an issue related to genetics and it would be extremely rare to have a hybrid registered that showed such a glaring default. Ear drop won’t be something that occurs in every field, even if conditions were the same all season long. This will be an effect of planting date, conditions at planting, silking date of the given field and other agronomic factors. In other words, not preventable and simply, bad luck.

To mitigate some yield loss at harvest, combine (or silage) affected fields before any others. When harvesting grain corn, raise header just below cob height and reduce both ground and header speed. When silaging corn, it would be ideal to also raise the header, though that is not going to be popular advice to give a grower. Instead, slow ground speed to the point that you see greatest ear retention.

If there was evidence of stalk rots or insect damage, consider using hybrids with appropriate traits in the future.

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Several dropped ears in silage field. Photo credit: Madison Leonard, Clearview Consumers Co-op Ltd., Steinbach, Manitoba.

Article written by Morgan Cott, Agronomy Extension Specialist – Special Crops with Manitoba Crop Alliance.

Estimating Yield and Physiological Maturity

mca2022dev on September 2, 2021

Producers and agronomists should be assessing each grain corn field now for yield estimates. Pollination is long since complete and we have an excellent idea of how many kernels have been pollinated.

The following is taken from Dr. R.L. (Bob) Nielsen on estimating corn grain yield prior to harvest. Dr. Nielsen has some excellent articles on corn production that are worth looking into. (www.agry.purdue.edu/ext/corn/news/timeless/YldEstMethod.html)

At each estimation site, measure off a length of a single row equal to 1/1000th acre. For 30-inch (2.5 feet) rows, this equals 17.4 linear feet.
TIP: For other row spacings, divide 43,560 by the row spacing (in feet) and then divide that result by 1000 (e.g., [43,560 / 2.5] / 1000 = 17.4 ft).

Figure 1. Row length required to measure 1/1000^th acre in various row widths – Ontario Grain Farmer (ontariograinfarmer.ca/2017/06/01/cropside-corn-stand-checkup/)

Count and record the number of ears on the plants in the 1/1000th acre of row that you deem to be harvestable.
TIP: Do not count dropped ears or those on severely lodged plants unless you are confident that the combine header will be able to retrieve them.
For every 5th ear in the sample row, record the number of complete kernel rows per ear and average number of kernels per row. Then multiply each ear’s row number by its number of kernels per row to calculate the total number of kernels for each ear.
TIPS: Do not sample nubbins or obviously odd ears, unless they fairly represent the sample area. If row number changes from butt to tip (e.g., pinched ears due to stress), estimate an average row number for the ear. Don’t count the extreme butt or tip kernels, but rather begin and end where you perceive there are complete “rings” of kernels around the cob. Do not count aborted kernels. If kernel numbers per row are uneven among the rows of an ear, estimate an average value for kernel number per row.
Calculate the average number of kernels per ear by summing the values for all the sampled ears and dividing by the number of ears.
EXAMPLE: For five sample ears with 480, 500, 450, 600, and 525 kernels per ear, the average number of kernels per ear would equal:
(480 + 500 + 450 + 600 + 525) divided by 5 = 511
Estimate the yield for each site by multiplying the ear number (Step 2) by the average number of kernels per ear (Step 4) and then dividing that result by a kernel weight “fudge factor”. Unless your seed company can provide some insight into kernel weight values for their hybrids, I suggest simply performing separate calculations using “fudge factor” kernel weight values equal to 75, 85, and 95. This range of values probably represents that most commonly experienced in the central Corn Belt.

Figure 2. Grain corn yield estimate formula – Iowa State University (crops.extension.iastate.edu/cropnews/2017/08/estimating-corn-yields-using-yield-components)

Example: Let’s say you counted 30 harvestable ears at the first thousandth-acre sampling site. Let’s also assume that the average number of kernels per ear, based on sampling every 5th ear in the sampling row, was 511. Using “fudge factor” values of 75, 85, and 95; the estimated range in yield for that sampled site would (30 x 511) divided by 75 = 204, or divided by 85 = 180, or divided by 95 = 161 bushels per acre.

Repeat the procedure throughout field as many times as you deem representative. Tally and average the results separately for each “fudge factor” used for the calculations.

Remember that this year we have very uneven uniformity in most corn fields, which will influence the accuracy of any yield estimation technique. The less uniform the field, the greater the number of samples that should be taken to estimate yield for the field.

Figure 3: Measurements for each reproductive stage of corn development and how a killing frost would affect yield at that stage.

In early September, we tend to estimate when the corn will reach physiological maturity even more than we estimate yield in each field. In recent years, Manitoba has been getting early to mid-September killing frosts, so the chart above has been a very well-used reference. If you need help determining stage of corn, visit Grain Fill Stages in Corn (Purdue University), or a simple Google search for countless resources on how to properly identify milk line or physiological maturity (black layer).

Article written by Morgan Cott, Agronomy Extension Specialist (Special Crops) with Manitoba Crop Alliance

Effects of Drought Stress on Corn

mca2022dev on July 13, 2021

In recent years, we have dealt with drought stress in corn a lot. Most frequently, it has been overcome by timely rains and not had an impact province-wide. 2021 doesn’t appear to be letting up on the crop completely and reproductive stages of corn are just around the corner. Some sheltered areas along tree rows and yards are even beginning to tassel.

So, what happens to the plant when there isn’t enough moisture? Most visibly, corn leaves begin to curl and make the plant resemble pineapple leaves or onion greens. This occurs because the leaves are protecting themselves from excessive moisture loss or transpiration. Believe it or not, the more readily a plant curls its leaves up, the more beneficial it is to that plant. This year it is hard to determine with absolute positivity whether those plants are protecting themselves, or really in dire straits for moisture availability. There is no question, though; leaf rolling is a response to moisture deficits and it is widespread. This transpiration increases as leaf area increases and it is the mechanism that water moves from the soil, through the plant and into the atmosphere. If leaf rolling is resulting from true drought stress and occurs for 12+ hours a day, grain yield is likely to decrease, even prior to reproductive staging.

Right now, mid-July 2021, the crop is at a detrimental stage for water requirements. The corn is a little behind “normal” as a result of the lack of moisture and high heat combination, so on a regular year the corn would likely be at tassel (VT) or silking (R1) stages. “Potential ear size is already determined by the time silks emerge from the ear shoots. In fact, potential kernel row number is set by the 12-leaf collar stage (about chest-high corn.) Potential kernel number per row is determined over a longer time period, from about the 12-leaf collar stage to about 1 week prior to silk emergence” (https://www.agry.purdue.edu/ext/corn/pubs/corn-07.htm).

We know that row number is heavily predetermined through genetics, but kernels per row is not and has a strong sensitivity to environmental stresses. Below is a table identifying the potential yield reduction from drought stresses (with 4 consecutive days of leaf wilting) throughout the growing season.

Severe drought stress has the greatest impact during silk elongation, which often results in poor pollination. Silks on the base of the ear begin to elongate first, followed by those from the center and then the tip of the ear. So, when plant water is in low supply, the silks elongate slowly and may not even elongate beyond the husk. If the silk isn’t outside the husk during pollen shed, it will not pollinate those potential kernels. During these conditions, silks that do emerge have an increased chance of desiccating quickly, making them unable to receive pollen.

There is no gain made in worrying about what may happen over the next few weeks. What is promising is that corn has an amazing ability to recover from drought stress when it does receive rain. It is very unlikely that no pollination will occur whatsoever, but if dry conditions persist, it is likely that grain will not fill to its full potential. This is where rain events can really improve grain quality and the length of the crop’s life after it has been under severe stress.

Farming through a drought is something Manitobans haven’t had to do in decades and it is a steep learning curve. The best thing you can do is choose wisely where to put crop inputs and where not to. Producers are all under a great deal of stress this year, but we are all here to provide each other with the support we need. This year is teaching us a great deal about what crops and what fields handle a lack of moisture the best, in the same way that we learned about excess moisture tolerance in past years.

With that being said… time to go fishing??