3 Questions to Ask Your Corn Seed Dealer about Goss’s Wilt Ratings

Goss’s Wilt was reported in several areas of Manitoba during the 2016 growing season. Goss’s Wilt is a bacterial disease and CANNOT be controlled by a fungicide. Managing Goss’s Wilt include weed control, tillage and most importantly rotation and hybrid selection (genetics!). And with the seed ordering season quickly upon Manitoba corn growers, here are 3 questions you should ask your seed dealer about Goss’s Wilt ratings.  The more information you have, the more informed decision you can make.

But before that, some key points:

  • there is no third party data available for Manitoba hybrids;
  • ratings will likely change over time as more years of testing are completed, in different locations and conditions;
  • resistance does not equal immunity! Plants don’t have immune systems and therefore can’t be immune to any disease. Depending on the level of disease pressure, hybrids that are rated as resistant/tolerant can still be infected to some degree. If disease pressure is high (i.e. high inoculum levels, conducive environmental conditions for a long period of time), yield loss due to Goss’s Wilt can still occur in the best rated hybrids.

But First! Before you start asking your seed dealer questions, if you experienced Goss’s Wilt this year perhaps there’s a few questions you can ask yourself (or your neighbor if they had Goss’s Wilt). Was Goss’s Wilt present in every corn field, just one or a few? What were the levels of Goss’s Wilt in individual fields? Do you (or your neighbor) know the resistance rating of those hybrids, both exhibiting symptoms or not exhibiting symptoms? Are you keeping good field notes? While there is no third party data available, you could start making subjective on-farm comparisons (but at the same time recognizing the limitations of those comparisons).

Question 1: What is the rating scale used?  Since there is no universal system for determining Goss’s Wilt ratings in Manitoba, there can be differences between companies and their hybrid ratings. For some companies, a rating scale of 1 to 9 is used, where 1=Poor and 9=Excellent.  However, other companies use the same 1 to 9 scale, but 1 = Resistant and 9 = Susceptible. Then there are others that only use a 1 to 5 scale.  So read the fine print….what does a 3 really mean? And remember, since there is no universal system in Manitoba, you can only really compare between hybrids within a single company.

Question 2: How is the testing done to establish the ratings? Ask if the testing is done under natural infection or through disease nurseries with inoculation.  Relying on natural infection to determine ratings is not as dependable as disease nurseries with inoculation (and wounding). Goss’s Wilt typically shows up in patches and can be very weather –dependent. Also, Goss’s Wilt needs an entry point, often caused by hail, wind damage, etc. No symptoms under natural infection may not indicate resistance, but instead conditions weren’t conducive for infection, i.e. escape.  Artificially inoculated nurseries may be resource intensive, but provide a better chance for determining resistance levels of hybrids being evaluated.

Question 3: Where is the testing done to establish the ratings? For some companies, testing is done in the United States, while other companies have established trials in Manitoba.  Why would this be important? There is variability in the pathogen population, where strains are separated into groups based on DNA analysis. Further research is on-going at the University of Manitoba with funding provided by the Manitoba Corn Growers Association and Growing Forward 2 to determine the strains of Goss’s Wilt present in Manitoba. We are only beginning to understand the pathogen population here in Manitoba so there is more research that needs to be done to fully understand the role of host resistance. In the meantime, testing conducted with disease nurseries and inoculation, either here or elsewhere, is a good step to provide information on hybrid resistance ratings.

Remember, resistance ratings to Goss’s Wilt is only one of many hybrid characteristics producers should consider when choosing their hybrid!

Written by: Pam de Rocquigny, Provincial Cereal Crops Specialist & Holly Derksen, Field Crop Pathologist, Manitoba Agriculture

For more information on Goss’s Wilt, visit Manitoba Agriculture’s website at https://www.gov.mb.ca/agriculture/crops/plant-diseases/goss-wilt.html

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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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VOLUNTEER CANOLA IN WINTER WHEAT – A CAUSE FOR CONCERN?

With good soil moisture conditions, warm soil temperatures and generally favorable weather, winter wheat is emerging quickly across Manitoba. However, those same conditions are also allowing volunteer canola to grow very well.  And in some cases, volunteer canola will be present in establishing winter wheat fields in higher than wanted populations.

There are really two camps in regards to management of volunteer canola post-emergence in winter wheat in the fall. One is to wait for the first killing frost of the fall to control the volunteer canola, with the assumption the weed pressure is not sufficient to impact yield or crop establishment.

The other is to remove the early weed competition through herbicide application. There are a few products available for fall application after winter wheat emergence for control of volunteer canola. These include a bromoxynil/MCPA ester tank mix, Infinity (pyrosulfatole & bromoxynil) and Simplicity (pyroxsulam – does not control Clearfield volunteer canola). However, remember that a fall application of 2,4-D or dicamba products is not recommended (or registered) as it can cause crop injury only seen the following year at heading, as well impact yield potential (see photos below).

2,4-D injury in winter wheat

2,4-D Damage to Winter Wheat (Photos by Manitoba Agriculture)

For more information on registered products, application timing and rates, refer to the Guide to Crop Protection at http://www.gov.mb.ca/agriculture/crops/guides-and-publications/pubs/crop-protection-guide-herbicide.pdf

If herbicide application is considered, are there economic thresholds available, i.e. what density volunteer canola will cause yield losses that are economically greater than the cost of control?  Unfortunately, there is limited data available to assist producers and agronomists. In a 2-year study done in Ontario, yield response to increasing volunteer canola densities was variable in both years of the trial (Table 1). In 2004, the volunteer canola plant density of 760 plants/m2 was significantly lower than the other treatments.  However, there were no statistical differences in winter wheat yield at the various volunteer canola densities in 2005. Therefore, ‘it is inconclusive as to the density of volunteer canola that will significantly reduce winter wheat yields’.

Table 1. Winter wheat yield at various densities of volunteer canola in Ontario (2004 & 2005).

Winter Wheat Yield at various densities of volunteer canola 2004 and 2005

Source: Controlling Volunteer Canola in Winter Wheat
by F. Tardif, P. Smith (University of Guelph) and M. Cowbrough, OMAFRA

 

Fertility Considerations – N Uptake. Another factor to consider with a significant growth of volunteer canola is the amount of nitrogen the canola is utilizing prior to being killed by fall frost or herbicide application. A former Manitoba Agriculture staff person based out of Stonewall did some investigating in fall of 2008 into how much N uptake by volunteer canola was occurring in one of his producer’s fields.

Volunteer canola in winter wheat

Volunteer Canola in a Winter Wheat Field near Stonewall, MB. (Photo by Manitoba Agriculture)

He collected and weighed volunteer canola plants from two locations (2.79 square feet area) in one winter wheat field in early October. The dry matter weight of volunteer canola was calculated to be 791 lbs of dry matter per acre.  The samples were also submitted for tissue analysis and test results indicated the total nitrogen content at 5.02%.  Using 5% for the total nitrogen content results in 39.5 lbs of nitrogen taken up by the volunteer canola to that point. However, much of that nitrogen would be released for the crop next year.

Some other points to consider is some of that nitrogen might be lost overwinter in wet conditions – so the canola is functioning as a ‘catch crop’. However, the bad news is if producers have applied N during seeding or later in the fall, the canola is tapping into ‘applied N’ which is not desirable. And as always, banding is better than broadcast, especially to limit weed uptake of N.

Submitted by: Pam de Rocquigny, Provincial Cereal Crops Specialist; Jeanette Gaultier, Provincial Weed Specialist; and John Heard, Crop Nutrition 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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Tips to Marketing Downgraded Crops

Over the past few weeks, we’ve heard about the impact of the poor weather conditions over the harvest period on the quality of harvested grain.  With the crop off the field and into the bin, marketing now becomes the focus of many producers.

In the attached article (updated from 2014) by Gary Smart, Farm Management Specialist with Manitoba Agriculture, he provides excellent information to cope with downgraded crops.  Some highlights include:

  • When marketing poor quality grain, be prepared and don’t panic, especially right at harvest time.
  • Know the quality and find a buyer who will offer the best value.
  • Take good samples. Without thorough samples, it is tough to know what is actually in the bin.
  • Communicate with the buyer if already some of this year’s crop is already contracted.
  • Unless cash flow is an issue on the farm, being patient could be the best action to take as new markets may arise for poor quality grain.

ARTICLE: Marketing Poor Quality Grain (2016)

For further information, support and resources, contact the Manitoba Agriculture’s Farm Management Team at http://www.gov.mb.ca/agriculture/business-and-economics/farm-business-management-contacts.html

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

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Minimum Air Temperatures – September 13/14, 2016

From Manitoba Agriculture’s AgWeather Program, a map showing minimum air temperatures reached September 13/14:

Picture1

In addition, the Crop Weather Report is a weekly summary of temperature (max., min., avg) and total rainfall along with seasonal accumulations of degree days, corn heat units and rainfall (actuals and % of normal) are provided for about 50 locations in the five regions.

Following are links to weather maps in pdf format for the time period of May 1st to September 11th:

The above maps will be updated every Monday during the growing season. They are available on the Manitoba Agriculture weather web site at http://www.gov.mb.ca/agriculture/weather/index.html .

For more information or to subscribe to the weekly Crop and Weather reports send your request to [email protected].

Follow Manitoba Agriculture on Twitter at @MBGovAg to get these seasonal reports and more.

 

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It’s That Time of Year – Talking Fall Frosts in Manitoba

UPDATED FROM ARCHIVED CROP CHATTER POST MADE AUGUST 15, 2013

As we enter in the later parts of the growing season, fall frost enters the minds of most people involved in the grain industry.  As everyone knows, frost can have an impact on a crop’s quality and yield.  There were a few areas reporting a light frost event the morning of September 14th.

The extent of frost damage to a crop will depend on several factors. The species, stage, and hardening of the crop, the soil type and soil moisture, the actual air temperature, the duration of freezing, and the rapidity with which freezing takes place are all important. A drop in air temperature of short duration will cause less damage than a prolonged periodthe same low temperature. When the air temperature drops to 0°C, cereal and other crops may not sustain damage. Rather, damage or total loss is more common when minimum temperatures drop below -2°C, often referred to as a killing frost.

Given its sporadic nature, long-range forecasting of frost is nearly impossible. Rather, the climate record of an area is used to determine probable dates of frost based on long-term temperature records. While this will not provide an actual frost date in a particular year, it will present the likelihood that frost may occur on a certain date. This can be a valuable planning tool.

The Manitoba Ag-Weather Program released updated FIRST FALL FROST MAPS in 2014 which are made from the new township gridded normal from a wider dataset of 1950-2010:

For additional information, please visit Manitoba Agriculture’s AgWeather Program at http://www.gov.mb.ca/agriculture/weather/agricultural-climate-of-mb.html.

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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So we had a Frost on our Soybean, Now what?

The first step in accessing frost damage is asking how cold it was last night. A light frost of -1°C for short durations may clip off a few off the top leaves with no effect on yield. The concern begins when a killing frost at least -2°C occurs for an extended period of time. In this situation you will see frozen leaves and pods throughout the canopy.  This may cause quality issues and yield reduction if the crop has not reached full maturity.

See the latest MB Ag Weather latest frost map: http://www.gov.mb.ca/agriculture/weather/pubs/minimum-air-temperature.pdf

What growth stage are your beans at, see http://www.manitobapulse.ca/soybean-staging-guide/ as a reference.

A killing frost at the R8 growth stage will see no yield or quality loss. The R8 stage is when the leaves have dropped off, all pods are brown, and seeds rattle within the pods when plants are shaken.

If however your beans are at the R7 growth stage, (which means one pod on the plant has reached its mature color), research has shown yield loss can range from 5-10 % dependent upon the severity of the frost. Quality issues in the way of green seed may also occur.

Finally, if your beans are at the R6 growth stage-(this is where pods containing a green seed that fills the pod cavity at one of the four uppermost nodes on main stem), yield losses can range from 20-30 %.  You will also have green seed issues which can also lead to marketing concerns.

There are a few areas in Manitoba where the beans are at the end of this R6 growth stage.  Most of the beans in Manitoba are at the R7-R8 growth stage. A light frost should not affect yield and quality for these beans. If beans were at the R6 growth stage and a hard frost occurred yield and quality losses would be noticeable.

IMG_1774

Picture: Light frost damage on soybeans near Hamiota, 2016.

Photo from L.Grenkow, Manitoba Pulse Soybean Growers

Submitted by: Dennis Lange, Industry Development Specialist-Pulses, Manitoba 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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Canadian Grain Commission’s Harvest Sample Program

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Photo Credit: Canadian Grain Commission

Mitchell Japp, the Provincial Cereal Crops Specialist with the Saskatchewan Ministry of Agriculture, recently wrote an article on the Canadian Grain Commission’s Harvest Sample Program – what it is, how to request a sample kit in order to submit a harvest sample, and getting results.  The complete article is available here: Harvest Sample Program.

The CGC is providing a valuable service to individual farmers and industry with the Harvest Sample Program, but it takes participation for it to work.  I would encourage Crop Chatter subscribers to click on the link and read Mitchell’s article!

 

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

For more information, visit the Canadian Grain Commission page.
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2016 Winter Wheat & Fall Rye MCVET Data Available!

Winter Wheat MCVET 2016Since 2008, MCVET (Manitoba Crop Variety Evaluation Team) has been publishing winter cereal yield data collected from their trials shortly after harvest to help farmers and seed growers in Manitoba make variety decisions.

In 2016, data is being released for 10 locations for 7 winter wheat varieties and 5 fall rye varieties: Fresh off the Field – 2016 MCVET Winter Cereal Yield Data

 

 

 

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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Seeding Winter Wheat? There’s Lots of Good Information on Crop Chatter!

With canola coming off in Manitoba, now is the time of year where producers are making plans to seed winter wheat.  There have been numerous posts on Crop Chatter regarding winter wheat production over the past year and I’ve summarized the most relevant ones to seeding below:

Another excellent source of information is the Western Winter Wheat Initiative website at: http://www.growwinterwheat.ca/. The Western Winter Wheat Initiative is a collaboration between Bayer Crop Science, The Mosaic Company Foundation, Richardson International, and Ducks Unlimited. It provides information and support in agronomy, products, and grain marketing to ensure winter wheat is a crop that is sustainable and profitable for farmers.  So check it out!

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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How Many Days Until My Grain Corn Reaches Maturity?

The 2016 season has seen normal to above normal accumulation of corn heat units (CHU), with a range of 95 to 117% of normal from May 1st to August 14th: Percent of Normal Accumulated Corn Heat Units. So as we inch closer to September, producers start to wonder when their grain corn may reach physiological maturity (R6).  At this stage, kernels have reached maximum dry matter accumulation and kernel moisture can range between 30 to 35% (but can vary by hybrid and environment).  But more importantly, at physiological maturity the grain corn crop will be safe from a killing frost.

The following table was modified slightly from the original table found in NDSU’s Crop & Pest Report August 8, 2013.  The table relates calendar days to corn kernel development and yield in general terms.

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

The ranges listed are fairly large in order to take into account variances in temperature (climate) and the relative maturities of the hybrids grown (genetics).   It is also important to remember that the various plant stages and the duration of those stages can also be influenced by soil fertility, cultural practices (plant populations) and water availability (dry conditions can hasten maturity).

Source:  NDSU Crop & Pest Report August 8, 2013 http://www.ag.ndsu.edu/cpr/plant-science/characteristics-of-late-maturing-corn-08-08-13

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

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

 

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Northern Corn Rootworm – Additional Established Populations Found in Manitoba

Established populations of Northern Corn Rootworm have been found in additional locations, as reported in the most recent Manitoba Insect & Disease Update – August 17, 2016.  The following is provided by John Gavloski, Provincial Entomologist with Manitoba Agriculture.

When corn is grown in the same field for several years in a row, it becomes more susceptible to various potential pests. One such pest is northern corn rootworm (Diabrotica barberi). Until last year only the occasional specimen of northern corn rootworm had been found in Manitoba, and not at levels that appeared to be an established population in a corn field. Last year we did find a well established population in a field in the Souris area. This year we are looking more intensively for them, and have found established populations in corn fields near Morden and Winkler. All fields where they have been found so far have had a long history of consecutive corn being grown in the same field.

This time of year you will see the adult beetles (Figure 1), often on the silks of the corn plants. These adult beetles are generally not of concern, and will lay eggs in the soil of the corn field they are in. When larvae hatch from these eggs the next spring, if there is corn in the field again they will feed on the corn roots. If corn is not in the field they will starve to death. Thus crop rotation is the easiest and cheapest way of dealing with them.

northern-corn-rootworm-on-corn

Figure 1. Northern Corn Rootworm

If anyone finds corn rootworm on their corn, or insects they think may be corn rootworm, we are trying to verify the range of this insect in Manitoba. So samples would be welcome and can be sent to John Gavloski, Manitoba Agriculture, Box 1149, 65-3rd Ave. NE, Carman, MB, R0G 0J0.

Visit the Insect Pages of Manitoba Agriculture’s website at: http://www.gov.mb.ca/agriculture/crops/insects/index.html

 

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Book Enough Winter Wheat Seed to Hit Your Target Plant Stand!

It’s that time of year when producers are booking their winter wheat seed. To order enough seed, you’ll need to know how much is needed for the acres you have planned – and you can go one step further than using the ‘rule of thumb’ of 2 to 2.5 bushels per acre.  To calculate seeding rate and how much seed is needed, the following critical pieces of information are required.

Target Plant Stand. For winter wheat, producers should be aiming for a target plant stand of 30 plants per square foot in the fall. In the spring, it is hoped established plant stand will be 25 plants per square foot to maximize yield potential and increase crop competitiveness.

Thousand Kernel Weight (TKW). TKW is what it sounds like – the average weight in grams of a 1000 kernels. There is variability between winter wheat varieties commonly grown in Manitoba. If looking at registration data, varieties such as Emerson or CDC Falcon had TKWs around 29 to 30 grams, while varieties such as AAC Gateway had a TKW of 32 grams and AAC Elevate had a larger seed size of 36 grams per 1000 kernels. Remember TKW can change yearly based on growing conditions – just because your chosen winter wheat variety was 32 grams in 2015 does not mean that it will be the same in 2016.

Expected Seedling Survival Rate. Expected seedling survival rate is the percent germination less an amount for seedling mortality.

The percent germination will of course be available from your seed retailer if you are booking certified seed. If considering using farm-saved seed, also be sure to test – and make sure a test is done after seed cleaning and at an accredited lab (and no…..kernels on a wet paper towel on a windowsill is not a germination test!!). Since most germination tests are relatively inexpensive, it is a small price to pay. And while you are having percent germination done, get the TKW as well.

The other factor of expected seedling survival rate is seedling mortality, i.e. what percent of viable seed will germinate but not produce a plant. I wrote a Crop Chatter post on April 26th asking readers if they’d considered their seedling mortality. The focus was on spring cereals, but the same principles apply to winter wheat as well. Seedling mortality can vary greatly from year to year, and field to field. For spring cereals, seedling mortality rates can range from 5 to 20%.  However, for winter wheat a seedling mortality rate on the higher end of the range should be used to take into account winter survival.

The Western Winter Wheat Initiative (www.growwinterwheat.ca) suggests using an expected seedling survival rate of 70%, which takes into account germination, emergence rate and the impact of winter survival.

So obtaining the above information may not be as easy as using a bushel per acre seeding rate. However, taking those extra steps will help ensure you are hitting your target plant stand – one of the first steps in setting your 2017 winter wheat crop up for success.

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

For more information on winter wheat production, visit Manitoba Agriculture’s website at http://www.gov.mb.ca/agriculture/crops/production/winter-wheat.html

 

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Preventing Stored Grain Insects at Harvest Time

#Harvest16 is here and a below is a quick review (from the most recent Manitoba Disease & Insect Update – August 10, 2016) of preventing stored grain insects from John Gavloski, Provincial Entomologist with Manitoba Agriculture.

Preventing stored grain insects: A reminder before moving and storing new grain to clean old grain out of bins, augers, combines, truck beds, and other areas where grain or grain debris may be. Infestations of stored grain insects such as rusty grain beetles usually do not get started by harvesting the insects along with the grain. They are often the result of insects already being present in bins or equipment used to move grain, or insects being able to get into the stored grain through openings in bins or storage structures. Figure 1 (below) is a picture of a sawtoothed grain beetle (top right), red flour beetle (bottom left), and rusty grain beetle (bottom right) with a grain of wheat (top left) to give perspective on size.

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Figure 1. Some beetles that may occur in stored grain.

Some insects in stored grain, such as the rusty grain beetle, will feed primarily on the grain, while others, such as foreign grain beetle, may be feeding primarily on molds growing on grain that is too moist. So it is good to know the species you are dealing with as management options may differ. Additional information on identifying and managing insects on stored grain can be found at: http://www.gov.mb.ca/agriculture/crops/insects/prevention-and-management-of-insects-and-mites-in-farm-stored-grain.html

For long-term storage of grain, lowering the grain temperature below 15C as soon as possible after the grain is placed in storage can help minimize the risk of stored grain insects. Below 15C potential insect pests of stored grain stop laying eggs and development stops. Grain that is not aerated or moved after harvest can often remain warm enough for insects to survive the winter.

Following proper storage recommendations is also a key component in Cereals Canada’s Keep It Clean initiative. More information is available at http://www.cerealscanada.ca/keep-it-clean/

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

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Are Herbicides Still Effective After a Fall Frost?

Fall is a great time to control perennials such as Canada thistle, perennial sow thistle and dandelion. As temperatures cool, nutrients move from the leaves down into the roots and if a herbicide can be taken up and translocated with those nutrients, it can equal better control. Glyphosate and/or the group 4s are examples of herbicides that provide effective fall control of perennials.

A frost event though, can kill some weeds or can damage leaf tissue which will reduce herbicide uptake and reduce the level of weed control. Within the next few days after the frost, you need to assess the target weeds in the areas that you want to obtain control – are the weeds still growing?  How much leaf tissue has been damaged?

Light frost: A light frost (0 to -3°C) can actually improve weed control by increasing herbicide translocation to the root. However, duration of the frost also plays a role. Check your weeds for frost damage if you plan on a herbicide application after a light frost. Herbicides can only be taken up and translocated by weeds that are healthy and actively growing.

If you do spray – spray in the afternoon when temperatures are warm and sunny, as this will help with herbicide uptake.   You’re looking for daytime temperatures of ~10°C for at least 2 hours. Use rates appropriate to the stage and time of year – fall applications of glyphosate are recommended at a higher rate than when controlling weeds pre-harvest.

Hard frost: Depending on the damage, a hard frost (≤ -5°C) can put an end to (effective) post-harvest weed control. However, if the plant leaves are still shiny green with minimal leaf tissue damage (i.e. not blackened/brown or brittle) or if less than 40% of the plant has more serious leaf tissue damage (i.e. blackened/brown or brittle) there may still be a window to make a herbicide application. Wait at least 48 hours before assessing frost damage after a hard frost.

If you do spray – read the ‘If you spray’ paragraph above, it still applies.  You need those daytime temperatures to hit ~10°C for at least 2 hours. In addition, consider your coverage – higher water volumes may improve uptake in more heavily damaged weeds.

One last thing – look at the forecast for the next week following the application.  If daytime temperatures are below 8°C and/or if night-time temperatures are forecasted to continually be below freezing, it may be too late to make the application to get the economic control you are looking for.

Visit Manitoba Agriculture’s Weeds webpage for more information on fall control of dandelion and quackgrass: www.gov.mb.ca/agriculture/crops/weeds/.

Submitted by Jeanette Gaultier, Manitoba Agriculture Weed Specialist

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Estimating Grain Corn Yields

The time of year is approaching where yield estimates can be done on grain corn.  Remember that grain corn yield is a function of the number of ears per acre, number of kernels per ear, and the weight per kernel.   Using the yield component method that was developed at the University of Illinois, yields can be estimated as early as the milk stage of development.

Calculating Estimated Grain Corn Yield:

Step 1.  Ear Number  – Using a row length equal to 1/1000th acre (row width 30 ” = 17′ 4″; row width 36 ” = 14′ 6”), count and record the number of ears in the length of row that are harvestable.

Step 2. Average Number of Kernels per Ear – Pick 3 representative ears and record the number of complete kernel rows per ear and average number of kernels per row.  Multiply each ear’s row number by its number of kernels per row to determine total number of kernels for each ear.  Calculate the average number of kernels per ear by summing the values for all the sampled ears and dividing by the number of ears.

Note – 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.

Step 3. Estimate yield by multiplying the ear number by the average number of kernels per ear, then dividing the result by 90:  Yield (bu/ac) = (ear number) x (average # of kernels per ear) / 90.

Note:  The value of 90  is a “fudge factor” for kernel weight and it represents the average number of kernels (90,000) in a bushel of corn at 15.5% grain moisture.  If grain fill conditions have been excellent (larger kernels, fewer per bushel), use a lower value (80).  If grain fill conditions have been stressful (smaller kernels, more per bushel), use a larger value (100).

Here’s an example:  Field has 30” rows.  You counted 24 ears (per 17’ 5” length of row).  Sampling three ears resulted in 480, 500 and 450 kernels per each ear, where the average number of kernels per ear would be (480 + 500 + 450) divided by 3 = 477.  The estimated yield for that location in the field would be (24 x 477) / 90, which equals 127 bu/ac.

Remember that yield estimates are only as accurate as the number of samples taken so repeating this exercise in several areas of a field will improve accuracy.  Since corn is in the early grain filling stages, water availability, insects, weeds, diseases, and other factors can still affect seed fill and therefore final yields.  However, as the plant approaches maturity, environmental stresses have less impact on final yield so yield estimates made that are closer to maturity should be more accurate.

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

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