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Verticillium Wilt of canola detected in Manitoba

Manitoba Agriculture, Food and Rural Development (MAFRD) has identified Verticillium wilt (Verticillium longisporum) in canola (Brassica napus) in Manitoba. This is the first time this disease has been detected in Canada.
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Symptoms of Verticillium wilt in canola as plant fully ripens (photo courtesy of MAFRD)

The disease was visually identified by the MAFRD Crop Diagnostic Centre on a canola sample submitted because patches of wilted canola were observed in a field. The pathogen culture was sent to the National Fungal Identification Service in Ottawa for molecular identification, which confirmed it as Verticillium longisporum.  MAFRD is working with the Canadian Food Inspection Agency (CFIA) to implement biosecurity risk mitigation measures where this pest was detected. The CFIA will conduct further surveying in spring 2015 to determine the spread of the pathogen.
For more information on:
  • Facts about Verticillium Wilt in Canola
  • Management of Verticillium Wilt in Canola
  • Symptoms of Verticillium Wilt in Canola at Harvest

visit MAFRD’s website at: http://www.gov.mb.ca/agriculture/crops/plant-diseases/verticillium-wilt-of-canola-detected-in-manitoba.html

A factsheet on Verticillium wilt in canola containing information on biology, symptoms of damage, scouting techniques, and control tips is also available on MAFRD’s website at http://www.gov.mb.ca/agriculture/crops/plant-diseases/verticillium-wilt-of-canola-factsheet.html

For more information, please contact MAFRD’s Crop Knowledge Centre at 204-745-5660
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Over the Course of Time: Manitoba Canola Diseases 2009-2014

Canola is one of the most economically important crops produced in Manitoba and yield robbers such as canola diseases need to be identified in order to apply best management practices. For many years, sclerotinia has been the most significant canola disease in Manitoba. However, in recent years the prevalence (% of fields infested) and incidence (% plants infected per field) of blackleg have been increasing.

Disease incidence and severity will change from year to year based on use of genetic resistance in varieties, environmental conditions, and agronomic practices such as crop rotation and fungicide use. Annual surveys of commercial canola crops provide valuable information on the distribution of disease, impact of farming practices on severity and incidence, help agronomists and farmer prioritize where future resources need to be directed, and can provide an early-warning system that provides information on the occurrence of disease/pesticide breakdown.

For more information on the annual Manitoba canola disease survey including methods, results from 2009 to 2014, and further discussion, please view the attached poster which was presented at the 2014 Manitoba Agronomists Conference:

Over the Course of Time Manitoba Canola Diseases 2009_2014 (Kubinec et al., 2014)

For more information on canola diseases in Manitoba, and information on various types of control methods, please visit MAFRD’s website at http://www.gov.mb.ca/agriculture/crops/plant-diseases/index.html
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Goss’s Wilt in Corn: 2014 Manitoba Disease Survey

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

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

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

Goss's Wilt survey map

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

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

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

Submitted by: Holly Derksen, Field Crops Pathologist, MAFRD

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Are Your Canola Swaths Turning Black?

Submitted by Holly Derksen, MAFRD Field Crop Pathologist

There have been a number of reports of ripe canola looking black or, in some cases, sooty. Upon closer examination, it looks as if a black mould is growing on senescing plants.

The good news, this sooty growth is caused by saprophytic fungi that only infect tissue that is already dead or dying – these are not pathogenic fungi, although they can be closely related to them. The bad news, in the fields we have been called to, the saprophytic fungi are growing on plants that are senescing earlier than other plants in the field due to the presence of disease, most notably blackleg.

So, although the black “mould” on the plants isn’t the issue itself, it can lead you into the field where you could discover an underlying problem. Once again, we recommend jumping off the swather with a pair of clippers, pulling up plants, and clipping them at the base of the stem to look for discolouration in the cross-section. You can’t do anything about the blackleg in this year’s crop, but the knowledge of its presence can help you with future management decisions. Rotation rotation rotation!!

 sooty mould canola 2014

sooty mould canola 2014-2

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Warm Soil Means Fast Emergence….So Go Scout!

With most soil temperatures across Manitoba averaging over 10C, and the good soil moisture, crops planted are emerging quickly!

So, great news, but what this means is it is time to get out and start scouting!

Things to look for are:

  1. Emergence, plant stands, patterns in field – this can indicate if seeds planted evenly, but can also you could indicate early issues like cutworms, soil-borne disease and herbicide residue injury.
  2. Weeds species, numbers and size – if you crop is coming up this fast, so are the weeds!  Targetting the weeds when they are small and knowing the species so you can choose the right product and the right will really help with the control.  Make sure those little yield-robbbers don’t get to use the sun, moisture and fertilizer instead of your crop.
  3. Insects – cutworms were mentioned before, but more look more specifically for the damage on the plants if you can’t see the insect, as that can help with identification.  Are leaves clipped off leaves at or above the soil vs. chewed with ‘shot-gun’ hole marks in leaves.  Keep in mind the economic thresholds for control!
  4. Other funny stuff ?  Keep these in mind too when out scouting and mark down spots (or GPS tag) to monitor as the days go on to see how they progress, sometimes it takes a couple of days before things become obvious.  When in doubt give the Crops Knowledge Centre a call at 204-745-5663.

Submitted by: Anastasia Kubinec, Oilseed Crop Specialist, MAFRD Crops Knowledge Centre.

Resources:

MAFRD Guide to Crop Protection: http://www.gov.mb.ca/agriculture/crops/guides-and-publications/index.html#gfcp

Weed Identification: http://www.gov.mb.ca/agriculture/crops/weeds/

Insect Identification: http://www.gov.mb.ca/agriculture/crops/insects/index.html

 

 

 

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Happy Robigalia!

The urediniologists at the USDA-ARS Cereal Disease Laboratory sent a greeting today, April 25th,  wishing everyone Happy Robigalia!

You might wonder what Robigalia is.  Instituted by Numa Pompilius (the second king of Rome), the Robigalia, an ancient agricultural festival celebrated in honor of Robigo (or Robigus, the gender was uncertain), the goddess of blight, red rust, or mildew, was celebrated on April 25, when the crops were most vulnerable to disease.  The Robigalia was one of several agricultural festivals in April to celebrate and vitalize the growing season.

The greeting was sent to members of the Cereal Rust Survey listserv list, whose purpose is to provide a format for cereal researchers and extension personnel to share observations of cereal rusts and other cereal diseases.  For more information on the “Cereal Rust Situation Reports” and “Cereal Rust Bulletins”, visit USDA-ARS website at http://www.ars.usda.gov/main/docs.htm?docid=9757

Submitted by:  Pam de Rocquigny, MAFRD Cereal Crops Specialist

 

 

 

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Why do we see disease in varieties that are rated “R” or “MR”?

Prepared by Holly Derksen, MAFRI Field Crop Pathologist

It is important to remember that resistance does not equal immunity.

In fact, plants don’t have immune systems so you can’t expect them to be immune to any disease. Depending on the level of disease pressure varieties that are rated as resistant will be infected to some degree. If disease pressure is high (ie. high inoculum levels, conducive environmental conditions for a long period of time) then you can still see yield loss due to disease in R-rated varieties.

 The infection that we see on the R-rated varieties is caused by the part of the pathogen population on which that type of resistance is not effective. If we grow varieties with the same type of resistance over a widespread area and in a tight rotation we select for that part of the pathogen population (sometime referred to as a different race). This is when we really begin to see issues, now the majority of the pathogen population cannot be controlled with resistant varieties. This is why it is important to use more than one management technique – do not just depend on variety resistance. It varies from disease to disease, but other management options include crop rotation, rotation of variety, fungicide application(s), tillage, etc.

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Why Do Sunflowers Do Poorly After Canola?

We don’t know all the reasons that sunflowers seem to do so poorly after canola, but the most likely culprit  is sclerotinia.  Sclerotinia kills or greatly reduces sunflower yields in three ways, throughout the season – basal rot (early), mid-stalk (mid-summer) and head rot (late summer).  Canola is also a host for the disease and sclerots from a previous year infection would be present and germinating  in very close proximity to the sunflower plants.  This would provide prime opportunities to cause multiple plants to be infected at different times in a growing season.  Yields  reported to MASC (MB Agricultural Services Corp.) in the Harvest Acreage Reports from 1998 to 2007, show sunflowers after canola yielding 87% as compared to the overall average sunflowers yield.

Other issues contributing to the yield reduction may also include common insects between crop species grown in succession, herbicide carryover, soil moisture availability and nutrient availability. 

For more information on growing sunflowers see: http://www.gov.mb.ca/agriculture/crops/oilseeds/bgd01s01.html

Specifically on Sclerotinia in sunflowers: http://www.gov.mb.ca/agriculture/crops/diseases/fac31s00.html 

Information on Re-cropping Restrictions for Residual Herbicides see the Guide to Field Crop Protection at: http://www.gov.mb.ca/agriculture/crops/cropproduction/pdf/gcp2012/herbicide.pdf

 

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