Testing Weeds for Herbicide-Resistance

Do you have weeds that survived this year’s herbicide application(s)? Since there are many factors that can contribute to weed escapes, consider:

  • The distribution of escaped weeds. Herbicide-resistant weeds tend to occur in patches as opposed to geometric patterns (e.g. spray miss) or throughout the field (e.g. tolerant weeds).
  • Possibility of reduced herbicide efficacy. 2016 was a challenging year for weed management due to untimely and excessive rainfall. In many cases, weeds escaped because of herbicide application timing with respect to weed growth stage, limited herbicide choices because of crop growth stage (when producers finally could get on their fields) and product rainfastness.
  • Weed species. Annual weed species, like wild oat, green foxtail, cleavers, kochia, hemp-nettle, smartweeds, ragweeds and wild mustard, may be more likely to develop resistance compared with other weed species. Because the development of herbicide-resistance is based on chance, resistant weed patches are typically a single species, as opposed to non-resistant weed escapes, which may affect multiple weed species.

Suspect weed escapes can be confirmed as resistant or susceptible by herbicide-resistance testing. For most weeds, dry, mature seed is required for the analysis.  Although more is better, many labs require at least 100 g of small weed seeds (e.g. cleavers) and 200-250 g of large weed seeds (e.g. wild oat).  Weed seed samples should be submitted by December 31st, 2016 to either:

For suspected glyphosate-resistant kochia, a genetic-based tissue test is also available from the Pest Surveillance Initiative: http://www.mbpestlab.ca/field-testing/. In this case, about 5 to 10 g of green plant tissue (e.g. leaves and stems from plant tips) is needed for the analysis. Samples should be placed on ice and shipped immediately after collection. The advantage of the genetic test (vs. seed analysis) for kochia is the ability to determine resistance in-season.


Submitted by: Jeanette Gaultier, Provincial Weed Specialist, Manitoba Agriculture

For more information on resistant weeds and weed management, visit the Manitoba Agriculture website: http://www.gov.mb.ca/agriculture/crops/weeds/


Have a follow-up question?

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 ~8 to 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 ~8 to 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.

Submitted by: Jeanette Gaultier, Provincial Weed Specialist, Manitoba Agriculture

Visit Manitoba Agriculture Crops webpage for more current topics: www.gov.mb.ca/agriculture/crops/seasonal-reports/current-crop-topics.html#agronomy; or the Manitoba Agriculture Weeds webpage for more information on fall control of dandelion and quackgrass: www.gov.mb.ca/agriculture/crops/weeds/.


Have a follow-up question?

What areas of Manitoba received the most rainfall in early October 2016?

The following precipitation maps are provided by Manitoba Agriculture’s Ag Weather Program.  The displayed map shows Total Accumulated Precipitation from October 2 to October 4, 2016.







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

Have a follow-up question?


Fall is the most effective time to manage certain weed species. The recommendations seem clear-cut:  winter annuals = fall herbicide application/tillage; annuals = no fall management.  But figuring out the life cycle of the weeds in your field this fall is the catch……

Bromes, cleavers, chickweed, night-flowering catchfly, narrow-leaved hawk’s-beard, shepherd’s-purse and stinkweed are all facultative winter annuals, meaning that they can germinate in either the fall or the spring depending on environmental conditions.  These weeds are often best managed in the fall, if populations warrant it.  In general, waiting until about this time of year maximizes fall-germinating flushes of winter annuals.  If using a herbicide, consider weed stage and the weather forecast, prior to application.

The problem is, given the right conditions – like the long falls and mild winters we’ve had the last few years –several of our annual weed species can also successfully overwinter:

Biennial wormwood – Despite its name, biennial wormwood behaves like an annual in agricultural fields.  When scouting, estimate the average growth stage of biennial wormwood populations in a field.  If the majority of the plants have already set seed, a fall herbicide application won’t help.  An application may be worthwhile only if there is a large flush of biennial wormwood that haven’t set seed and are less than ~3 inches tall.  Herbicide tank-mixes containing glyphosate + group 4 are more effective than glyphosate + group 2 on this weed.

Round-leaved mallow (RLM) – This annual weed can act as either a winter annual or a short-lived perennial, although it is more sensitive to freezing than our common winter annuals.  Mild winters in 2015 & 2016 provided the right conditions for RLM to overwinter, allowing it to become (even more) problematic in certain fields over the last few growing seasons.  Long range forecasters are predicting a harsh winter across the prairies this year, which should control RLM.  However, if you have little faith in forecasts and decide to apply a herbicide, glyphosate mixed with either Distinct or DyVel DSp has activity on this weed.


Round-leaved mallow post-harvest

Stork’s bill –
Like biennial wormwood, stork’s bill tends to be predominantly an annual in Manitoba.  If this is a problem weed for you, scout affected fields to determine average weed stage.  Again, if most of your stork’s bill has set seed you’re better off working on a plan for next year.  Stork’s bill, especially larger plants, is relatively tolerant of many herbicides.  If you decide to apply a herbicide because of stork’s bill this fall, glyphosate + group 2 or glyphosate + group 2 + group 4 on weeds up to the 4 to 6 leaf stage is probably your best bet.

Submitted by: Jeanette Gaultier, Provincial Weed Specialist, Manitoba Agriculture

Information on more weeds and their life cycles is available at: www.gov.mb.ca/agriculture/crops/weeds/
Have a follow-up question?

Winter Wheat Survival – Impacted by Fall Management Decisions & the Weather!

For winter wheat, survival through our cold Manitoba winters is directly influenced by fall management decisions, including variety selection, seeding date and depth, adequate plant stands, fertility and stubble height/density. Optimal winter survival can also be influenced by fall weather conditions and snow cover.

What is the ideal situation heading into the winter?

  • Plant stage would be at the 3 to 4 leaf with 1 to 2 tillers, and well developed crown tissue.
  • Cool conditions in the fall, where plants would grow for 4-5 weeks, followed by 4-8 weeks (October to November) of growth that allowed plant to acclimate (harden off) and vernalize (giving the plant the signal to flower next spring).
  • A minimum of 4 inches of trapped snow cover through December to early March to buffer soil temperature changes and provide protection to the crown tissue.

What is cold acclimation and vernalization? 

Cold Acclimation. The ability of the winter wheat plant to survive the winter often depends on its ability to withstand low temperatures.  Under normal field conditions, eight to twelve weeks of growth is usually required for the full development of winter hardiness.  The first four to five weeks is a period of active growth that takes place when average daily soil temperatures at a depth of two inches (5 cm) are above 9°C. Both the cold acclimation process and winter survival require energy and this period of warm temperature allows for the establishment of healthy vigorous plants. Plants with well developed crowns before freeze-up are most desirable.  However, plants that enter the winter with two to three leaves are usually not seriously disadvantaged.

Cold acclimation of winter wheat plants begins once fall temperatures drop below 9°C.   In the field, four to eight weeks at temperatures below 9°C is usually required to fully cold harden plants. However, regardless of the amount of cold acclimation, the wheat plant must receive insulating snow cover to survive the cold prairie winters.

Vernalization. During the period of cold acclimation, the low temperatures also initiate in the plant a physiological response called vernalization.  During vernalization, the plant converts from vegetative to reproductive growth and the reproductive structures are developed.  Because of this vernalization requirement, winter wheat produces only leaves for both the main stem and tillers aboveground in the fall in preparation for winter.  The growing point and buds of both the main stem and tillers remain belowground, insulated against the cold winter temperatures. Once vernalization requirements are met, the growing point differentiates and develops an embryonic head.  At this time, wheat head size or total number of spikelets per head is determined.  What is important to note here is neither seedling growth nor tillering is required for vernalization to occur.  This process can begin in seeds as soon as they absorb water and swell.  Hence, late planted wheat that has not emerged prior to winter should be adequately vernalized.   Or in extreme conditions, vernalization may occur under cool spring conditions.

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
Have a follow-up question?

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

Have a follow-up question?

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
Have a follow-up question?


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


Have a follow-up question?

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

Have a follow-up question?

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.


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


Have a follow-up question?

Canadian Grain Commission’s Harvest Sample Program


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.
Have a follow-up question?

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.


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


Have a follow-up question?

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.


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

Have a follow-up question?

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 

Have a follow-up question?

Minimum Air Temperatures – September 13/14, 2016

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


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.


Have a follow-up question?