Why is the 2017 Guide to Crop Protection SO BIG?

If you’ve picked up a copy of the 2017 Guide to Crop Protection, you’ve probably noticed that it’s BIG! (Sadly, more crop protection products are not the reason why).

The extra 100+ pages of the Guide are largely due to the new single column format with larger font (Figure 1). These changes were made to improve the readability of the Guide.

Other changes to the 2017 Guide include:

  • Placement of the Pesticide Index, which you can now find at the back of the book.
  • Information on maximum residue limits (MRLs) on page 6. Crop protection products flagged by the Keeping It Clean initiate also have a statement on the product pages in the Guide.
  • The herbicide site of action table on page 44 now also separates active ingredients and products by their chemical family to assist with herbicide resistance management.

The Guide to Crop Protection can be purchased for $10.00 at Manitoba Agriculture offices. A pdf version of the Guide is available at: www.gov.mb.ca/agriculture/crops/guides-and-publications/#gfcp

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Waterhemp Now a Manitoba Weed

Can you identify the plants in the two pots below?

waterhemp-and-redroot-pigweed

The plants on the right are redroot pigweed (Amaranthus retroflexus); the plants on the left are waterhemp (Amaranthus tuberculatus).

Unfortunately, the need to distinguish between these closely related weed species has become a reality for Manitoba producers and agronomists since waterhemp was found in the province in the fall of 2016. Suspect plant specimen collected from a soybean field in the RM of Taché was verified as waterhemp by staff with the Agriculture and Agri-Food Canada Collection of Vascular plants in Ottawa.  Waterhemp occurs in neighbouring states and provinces, including Minnesota, North Dakota and Ontario.

Both species thrive in agricultural fields where they compete with crops for nutrients, moisture and light. Waterhemp has no hairs on its stem or leaves, which can be used to distinguish it from redroot pigweed when plants are small.  The lack of hairs give waterhemp leaves a ‘glossy’ look unlike that of the ‘dull’ green leaves of redroot pigweed.  Also, waterhemp leaves are lanceolate in shape (longer than they are wide) compared to the more ovate leaves of redroot pigweed.  Colour is not a reliable identifying characteristic since both species can be green, red or variations of the two colours.

Mature waterhemp plants tend to be more branched than redroot pigweed. And unlike redroot pigweed, which has male and female flowers on the same plant, waterhemp has separate male and female plants.  Waterhemp inflorescence are long, slender and vary in colour compared with the compact, prickly inflorescence of redroot pigweed.  Like most pigweeds, waterhemp is a prolific seed producer with up to a million seeds per plant (under ideal conditions).

Waterhemp populations resistant to group 2, group 9 (glyphosate) and group 2+9 exist throughout the US, including Minnesota and North Dakota, and in Ontario. Seed from one of the plants found in Manitoba have been sent to Ontario for resistance testing.

Information on waterhemp will be added to Manitoba Agriculture’s weeds webpage shortly (http://www.gov.mb.ca/agriculture/crops/weeds/) and will be included at the Weed Seedling Identification Day (hosted by the Manitoba Weed Supervisors Association).  Manitoba Agriculture staff will conduct a waterhemp surveillance program in and around the RM of Taché in 2017.

Additional information on waterhemp is available at: http://www.extension.purdue.edu/extmedia/BP/gwc-13.pdf (excluding herbicide recommendations).

waterhemp-tone-ag-consulting

Photo: Waterhemp in Manitoba, Tone Ag Consulting

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

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A Look at FDK & DON in Winter Wheat Varieties

In 2014, a study was initiated to evaluate how winter wheat varieties being tested post-registration by MCVET respond to fusarium head blight under non-misted conditions (natural infection) by assessing harvested samples for fusarium damaged kernels (FDK) and deoxynivalenol (DON) accumulation. The results from 2014 can be found here: Winter Wheat Varieties Response to Fusarium Head Blight in 2014 and Effect of Fusarium Head Blight on Winter Wheat Varieties in 2014.

2015 Results. With funding from Winter Cereals Manitoba Inc., the study continued in 2015. Composite samples of eight registered winter wheat varieties were collected from the three replicates at four MCVET sites: Carman, Hamiota, Melita & Minto.  BioVision Seed Labs in Winnipeg, Manitoba conducted the analysis. The level of FDK (%) was measured as per the Official Grain Grading Guide of the Canadian Grain Commission. The accumulation of DON (ppm) was measured using the ELISA test method.

The variety Emerson, rated as Resistant (R), had lower levels of FDK and DON compared to the other varieties (see Figure 1).  Some varieties rated as Susceptible (S) consistently showed higher FHB severity, FDK and DON levels across all sites. However, data also shows there is variability of performance within the five resistance categories of Resistant (R) to Susceptible (S).

Figure 1: Average Levels of Fusarium Damaged Kernel (FDK) and Deoxynivalenol (DON) by Winter Wheat Variety at Four MCVET Sites in 2015

2015-average-don-fdk-at-four-mcvet-winter-wheat-sites

Figure 2: Fusarium Damaged Kernel (FDK) and Deoxynivalenol (DON) Comparisons at Four MCVET Sites for Winter Wheat Varieties in 2015.

2015-fdk-don-comparisons-at-four-mcvet-winter-wheat-sites

 

2016 Results. In the 2016 Manitoba Fusarium Head Blight Survey, the average FHB index for winter wheat was 2.7% which was slightly below the 10-year-average (3.1%).  Winter Cereals Manitoba Inc. again is providing funding to have the MCVET winter wheat varieties tested for FDK and DON. Analysis is currently underway and results should be available for the Winter Cereals Manitoba Inc. Annual General Meeting on March 15, 2017.

Summary. Extensive research over the past 20 years shows using multiple management options, including crop rotation, fungicide application and variety selection, is the best way to mitigate the risk of FHB. Although FHB infection will always be highly influenced by environment, the first step is to select varieties with improved resistance and then use them in combination with other management strategies. In years where there is higher disease pressure, such as 2014, variety selection will be critical to minimize the impact of FHB on yield and quality. However, under high disease pressure yield and quality loss due to FHB can still happen in varieties that have improved resistance as resistance does not equal immunity.

Remember, caution must be used with one year of data, as presented here. Using data derived over two or more growing seasons over multiple sites is always recommended to provide the best indicator of variety performance.

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

Special thanks to: Winter Cereals Manitoba Inc. for providing funding to conduct FDK & DON analysis; BioVision Seed Labs who conducted the FDK and DON analysis; Manitoba Crop Variety Evaluation Team (MCVET) & contractors who provided the harvested samples.

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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.

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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/

 

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ANNUAL OR WINTER ANNUAL?

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.

IMG_20150915_081215

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/
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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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Minimum Air Temperatures – September 13/14, 2016

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

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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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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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Corn Cobs in Tassels – What is the Cause?

Updated from a Crop Chatter post made August 2012

In talking with Morgan Cott, Agronomist with the Manitoba Corn Growers Association, producers are reporting seeing corn cobs in the tassel of plants. Although relatively uncommon, this phenomenon called ‘tassel-ear’ is reported almost every year.  A tassel-ear is very noticeable in the field and is often found on tillers of a corn plant along the edges of a field or in areas of low plant populations. Although it is uncommon to find tassel-ears that develop on the main stalk of a corn plant, it can happen.

Tassel Ear (P.de Rocquigny, 2015)

Tassel-Ear in Corn (Photo by P. de Rocquigny, 2015)

So How Do Tassel Ears Happen? A corn plant has a monoecious flowering habit where the plant has both male and female flowers.  What many may not know is that both flowers are initially bisexual.  During the course of development the female components (gynoecia) of the male flowers and the male components (stamens) of the female flowers abort, resulting in tassel (male) and ear (female) development.

Now every once in a while, the upper flower that typically becomes a tassel instead forms a combination of male and female floral parts on the same reproductive structure. The physiological basis for the survival of the female floral parts on the tassel is likely hormonal, but the environmental “trigger” that alters the hormonal balance is not known.

It has been noted that can be varietal differences where different hybrids produce ears in the tassel and is linked to a particular set of genetics. Ear development in the tassel may also occur when the plant sustains hail or mechanical damage early in its development.  Pollen shed would not have been affected, nor will yields be decreased as a result of this phenomenon.

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

For more information on the production and management of corn, please visit Manitoba Agriculture’s website at:  http://www.gov.mb.ca/agriculture/crops/specialcrops/bii01s01.html

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STAGE CEREAL CROPS CORRECTLY FOR A PREHARVEST GLYPHOSATE APPLICATION

Modified from Post Originally Published July 30, 2014

Staging a crop for preharvest glyphosate application for perennial weed control can be difficult when there is variability of crop staging within the targeted field.  As well, kernels in the same spike will reach physiological maturity at different times, with the middle of the head maturing first. To go back to the basics, for wheat you want to apply the preharvest glyphosate when grain moisture of the wheat crop is less than 30%.  In terms of visual assessment, the wheat crop must be in the hard dough stage.  This is when the kernel has become firm and hard and a thumbnail impression remains on the seed (see Figure 1).  Remember….you can’t rely on the color of the field as an indicator.  Walk the field and hand thresh heads to determine kernel staging.

Figure 1:  Kernels at various times during grain filling: a) kernel at watery ripe, b) kernel at late milk, c) kernel at soft dough, d) kernel at hard dough showing loss of green color, and e) kernel ripe for harvest.

Source:  Growth and development guide for spring wheat. 1995.  S.R. Simmons, E.A. Oekle & P.M. Anderson.  Photographer:  Dave Hansen.

 

Another visual indicator for wheat is a change in color of the peduncle, which is the part of the stem located just below the head.  It will have turned very light green or yellow at physiological maturity (Figure 2).

wheat_spikes
Source: Topics Addressing Small Grain Crop Dry-down and Harvest . 2015. Jochum Wiersma, Small Grains Specialist; Doug Holen, Crops Extension Educator and Phyllis Bongard, Educational Development and Communications Specialist

 

So what is special about this 30% moisture content?  At the end of the hard dough stage, the kernel has reached its maximum dry weight and the wheat is therefore physiologically mature, i.e. no more weight is added to the grain.  Therefore, final yield has been determined.

If application of a preharvest glyphosate occurs prior to the 30% moisture content, yield can be reduced, along with quality factors such as test weightIn addition, early application prior to the recommended timing may result in grain with glyphosate levels above maximum residue limits.  This could have implications depending upon target market.

So in timing an application on a variable field, this will be difficult but remember its likely better to apply on the later side than too early.  Also remember that depending on weather conditions, glyphosate can take up to 2 weeks for optimal weed control. However, under hot, dry conditions harvest could commence is as little as 7 days after application.  So keep harvest timing and weather forecasts in mind as well when planning your preharvest application.

Notes: Do not apply to wheat, or any crops, grown for seed.  Not all glyphosate products are registered for preharvest application on all crop species – always refer to individual crop labels for a list of registered uses and crop species. Check with malt barley or milling oat buyers prior to application to confirm acceptance of glyphosate-treated grain.

Following label instructions and keeping in mind pre-harvest intervals are also 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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