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      Wednesday, April 23, 2014

Developed by the Saskatchewan Clubroot Initiative
March 2013 

Clubroot Overview

What is clubroot?

Clubroot is a soil-borne disease caused by a microbe, Plasmodiophora brassicae. Clubroot affects the roots of cruciferous field crops such as canola, mustard, camelina, oilseed radish, taramira and cruciferous vegetables such as arugula, broccoli, Brussels sprouts, cabbage, cauliflower, Chinese cabbage, kale, kohlrabi, radish, rutabaga and turnip. Cruciferous weeds (e.g. stinkweed, shepherd's purse, wild mustard) can also serve as hosts.

What are the symptoms of clubroot?

Invasion of the interior of host roots alters hormone balance and leads to increased cell division and growth, resulting in clubroot galls. These deformed roots have a reduced ability to absorb water and nutrients leading to stunting, wilting, yellowing, premature ripening and shrivelling of seeds. The cause of these above-ground symptoms can be confirmed by digging up suspect plants to check roots for gall formation. Clubroot affects canola yield and quality to a similar degree as other diseases affecting water and nutrient uptake, and its impact depends on soil conditions and the growth stage of the crop when infection occurs. Early infection of seedlings tends to result in great yield losses. Spore germination in Plasmodiophora, infection and disease development are favoured by warm soils, high soil moisture and low soil pH.

Is there surveillance in place for clubroot?

A canola disease survey is conducted annually in the province by a collaboration of plant pathologists, agronomists and crop specialists from the Saskatchewan Ministry of Agriculture, Agriculture and Agri-Food Canada and private industry. The objective of the canola disease survey is to monitor the presence and severity of common canola diseases, as well as detect the appearance of new diseases such as clubroot.

Where has clubroot been found?

Clubroot affects crucifers worldwide, and was first identified in Europe in the thirteenth century. In Canada, clubroot is primarily established in vegetable growing regions of British Columbia, Quebec, Ontario and the Atlantic provinces. It has also been found in canola in Quebec since 1997. After 45 years of large scale production of canola in western Canada, the disease was reported for the first time in this crop near Edmonton, Alberta. Since then, clubroot has been confirmed in more than 15 counties in Alberta, and was added as a declared pest to Alberta's Agricultural Pests Act in 2007.

Clubroot symptoms have not been observed on any of the Saskatchewan canola crops randomly selected for canola disease surveys. In 2008, 30 soil samples were tested using both DNA diagnostics to detect Plasmodiophora brassicae and a bioassay in which canola plants are grown in a sample of the soil and observed for clubroot symptoms after six weeks. One soil sample from west-central Saskatchewan was found to be positive for clubroot using these tests, despite the absence of symptoms in the crop.

How does clubroot spread?

Infected roots will eventually disintegrate, releasing resting spores into the soil, which may then be transported by wind, water erosion, animals/manure, shoes/clothing, vehicles/tires or earth tag on agricultural or industrial field equipment. Resting spore numbers will decline over time when non-host crops are grown, but a small proportion can survive in soil for up to 20 years. Clubroot is primarily a soil-borne disease; it does not infect seed but it may be found in soil attached to seed or other plant parts. Clubroot does not present any legal phytosanitary issues for trade.

What is the oil and gas industry doing about clubroot?

The Canadian Association of Petroleum Producers has developed a set of best management practices designed to promote the development of effective and achievable procedures to minimize the spread of clubroot pathogen spores in areas in which susceptible crops are grown.

What are growers doing about clubroot?

Those who grow susceptible host crops should follow the recommended best management practices. These include proper crop rotation and sanitation for prevention and management of clubroot. Growers are advised to scout susceptible crops diligently and contact the Saskatchewan Ministry of Agriculture if clubroot is suspected.

Currently, fungicides are not a practical solution for clubroot in canola and there are no foliar products or seed treatments registered for control of clubroot on canola in Canada. Most Canadian canola varieties are susceptible to clubroot, but resistant varieties are becoming available in the marketplace.

Growers are also funding clubroot research through their canola levy. Saskatchewan researchers at Agriculture and Agri-Food Canada in Saskatoon are working in collaboration with the University of Alberta (U of A), Alberta Agriculture and Rural Development (AARD), the University of Guelph, and Ibaraki University in Japan to isolate, screen and discover indigenous microorganisms for biological control of clubroot on canola. The research is part of an integrated disease management approach supported by provincial canola development commissions and grower associations, and the Canola Council of Canada. Researchers at the U of A and AARD have also been studying the pathogen and control options, and both public and private research programs have been screening Brassica germplasm and developing clubroot resistant or tolerant canola lines for western Canada.

What are canola industry organizations doing about clubroot?

The industry organizations are assisting growers through education and awareness for the prevention of the spread of clubroot in Saskatchewan. The organizations help direct the canola levy to appropriate research initiatives which include the development of clubroot tolerant and resistant canola varieties. The canola industry organizations are also assisting the Saskatchewan Ministry of Agriculture through the Saskatchewan Clubroot Initiative.

What is the province doing about clubroot?

As part of a provincial clubroot management plan, the Saskatchewan Clubroot Initiative was established to promote awareness and identify priorities for clubroot prevention and management. In June 2009, the Saskatchewan Minister of Agriculture declared clubroot a pest, giving municipalities powers to handle clubroot under The Pest Control Act. These powers include the appointment of Pest Control Officers to enforce, enter land, perform inspections, collect specimens or issue orders to any person; the authority to pass bylaws to prevent, control or destroy clubroot; and the ability to require individuals to take actions to control or destroy clubroot on the land they own, occupy or control. Education and awareness continue to be a priority to help growers and industry members prevent the spread of clubroot into and within Saskatchewan.

Where can I get more information?

For more information on clubroot, please visit http://www.clubroot.ca/,visit the Ministry of Agriculture website at www.agriculture.gov.sk.ca or contact the Agriculture Knowledge Centre at 1-866-45-2377.

Objective

To promote awareness and minimize the risk of clubroot in Saskatchewan.

Best Practices for Prevention and Management

  • Plant susceptible crops, including clubroot resistant canola varieties, no more than once every four years. Crop rotation will not prevent the introduction of clubroot to fields that are free of the pathogen, but it will restrict clubroot development by limiting the increase of clubroot resting spores and preventing the increase of clubroot inoculum, as well help alleviate the impact of other plant pathogens.
  • Scout crops regularly and carefully.
    • Identify suspicious above-ground symptoms including wilting, stunting, yellowing and premature ripening of canola or other susceptible crops.
    • Wilting is likely to be more apparent in hot weather (usually afternoon).
    • Field entrances and approaches are likely to be contaminated with clubroot spores first. Therefore, symptoms will often appear there first.
    • Confirm cause of above ground symptoms by checking the roots for galls.
    • If clubroot is suspected, inform the Saskatchewan Ministry of Agriculture by contacting the Agriculture Knowledge Centre at 1-866-457-2377 or visiting your nearest Regional Office.
  • Practice good sanitation by restricting movement of potentially contaminated soil to non-contaminated regions.
    • For Saskatchewan producers, this means restricting entry into their fields of vehicles, field machinery or oil rig equipment with earth tag from infested regions unless it has been properly sanitized. Ask questions about where the equipment is from and what sanitation measures have been used before the equipment left the infested area, dealer or auction site.
    • Cleaning steps may include: removal of crop debris and soil, washing of equipment with a power washer using hot water or steam and misting with disinfectant (one or two per cent bleach solution), followed by an additional rinse with water.
  • Clubroot spores may survive livestock digestion. Avoid use of straw, hay, greenfeed, silage and manure from infested or suspect areas.
  • The risk of spreading clubroot through contaminated seed or plant material is much less than through transporting contaminated soil on field equipment and vehicles. However, avoid seed with earth tag from infested areas to prevent introduction to clean fields.
  • To minimize the risk of accidental release of P. brassicae, appropriate containment guidelines should be followed when conducting research involving P. brassicae in greenhouses, growth cabinets or laboratories.  Because clubroot is not widespread in Saskatchewan, field plot research should not be conducted here.  Preventative measures should also be followed when conducting disease surveys in Saskatchewan.  Contact the Agriculture Knowledge Centre for a copy of the current Recommendations for Managing Risks associated with Clubroot Research in Saskatchewan.

 

Confirmation of clubroot requires observation of disease symptoms in a susceptible plant as well as detection of the pathogen's DNA in a plant or soil sample.  If DNA test results are positive for clubroot despite an absence of symptoms in the plant surveyed, a follow-up bioassay (susceptible plants are grown in a sample of the soil and observed for clubroot symptoms after six weeks) is required to dispel false-positives and prove pathogen viability. If either DNA test results or plant symptoms indicate presence of clubroot without the combination of both, this is still deemed ‘unconfirmed'.  In fields where clubroot has been confirmed through the observation of disease symptoms in a susceptible crop and the detection of the pathogen's DNA in a plant or soil sample, the following measures should be taken:

  1. Plant susceptible crops, including clubroot resistant canola varieties, no more than once every four years, and rotate sources of disease resistance. Resistance to clubroot does not mean full immunity to the disease. Tight rotations of resistant varieties may lead to propagation and spread of new clubroot pathotypes that the variety has no resistance to, breaking down the effectiveness of the clubroot resistance. Although the signs and symptoms of clubroot may not be present, plants may still host disease and propagate new spores, increasing the potential severity of the disease in the future; therefore a minimum of four years is required between susceptible crops, including clubroot resistant canola varieties.
  2. Minimize traffic to and from fields and practice good sanitation by restricting movement of soil from the contaminated field to other areas. Any individuals or companies who may be accessing the land should be informed that clubroot is present on the land so they may limit traffic and/or ensure proper sanitation. Procedures for proper sanitation are outlined in point number three of the previous section.
  3. If infestation is only near the current field access, consider seeding perennial grass to that area and create a new access point as far from the contaminated area as possible.
  4. Use direct seeding and other soil conservation practices to reduce erosion. Resting spores can be readily moved in soil transported by wind or water erosion. Reducing the amount of tillage will reduce the spread of the organism within the field and to other fields.

Sampling for Clubroot Testing

As clubroot may take six to eight weeks to develop, symptoms are most detectable later in the growing season (late July or August).  Soil samples can be collected at any time but soil should be dried after collection. Do not drive into field or access, but park on the road whenever possible. Follow sanitation procedures if visiting more than one field.  Dispose of or clean and disinfest footwear and tools that come in contact with the soil.  Keep records for all fields visited.

In fields that have been confirmed for clubroot, sampling can be expanded in intervals of 150 metres from the field entrance or other location of the initial finding, in order to ascertain the extend of infestation.

 

Plant Sample Procedure:

  1. Collect 20 plants at each of five sites in the field, for a total of 100 plants and observe for disease symptoms. Each of the five sites need to be at least 20 metres from each other and at least 20 metres from the field edge.
  2. If patches of premature ripening are observed, particularly in field entrances or corners, dig or pull up plants, shake off excess soil and inspect roots for the presence of galls. If clubroot is suspected, cut off stems and collect root samples.
  3. Air-dry root samples in a double paper bags or freeze the samples in a double Ziploc bag (samples must remain frozen if this option is chosen). Send them to the Ministry of Agriculture's Crop Protection Laboratory at 346 McDonald Street, Regina SK, S4N 6P6 telephone (306) 787-8130. You may mail, courier or drop off samples in person. There is a $20 fee for visual inspection.
  4. If the visual diagnosis is positive, root samples will be forwarded to an accredited laboratory on behalf of the municipality for DNA testing. Cost of the DNA testing will depend on the current fee set by the accredited laboratory (approximately $100).

 

Soil Sample Survey Procedure:

  1. Soil samples should be comprised of a mixture of small scoops (approximately one cup each) of soil taken at each of five sites visited in one field. Because clubroot is most likely to arrive on soil attached to vehicles and field equipment. If the entrance to the field is evident, these five sites should be located in the vicinity of this approach. Otherwise, keep each of these five sites at least 20 metres from each other and at least 20 metres from the field edge.
  2. Clear away residue from the soil surface, and scoop approximately one cup of the top zero to 10 cm of soil at each site (total one litre from all five sites combined).
  3. Air-dry soil samples in paper boxes and send them to a laboratory for DNA testing. Cost of the DNA testing will depend on the current fee set by the credited laboratory (approximately $100).
  4. For a list of laboratories providing clubroot testing, please visit: http://www.clubroot.ca/ (click on Identify Clubroot) or contact the Crop Protection Laboratory in Regina.

Responsibilities

1. Saskatchewan Ministry of Agriculture

  • Co-ordinate efforts to monitor crops in the province for clubroot.
  • Compile and distribute the Saskatchewan Clubroot Management Plan.
  • Manage legislation and regulations pertaining to clubroot as a declared pest.
  • Extend clubroot education to the agriculture industry and the general public, as well as provide information to the oil and gas industries, environmental companies, landscaping companies, equipment dealers and auction companies and custom applicators, seeders, and harvesters.
  • If clubroot is confirmed through disease surveys or reported to the Ministry by an individual, company, or RM, the Ministry will first assess whether the report satisfies the requirements of clubroot confirmation. The report will be considered confidential and communication will not proceed until clubroot is confirmed.
  • The Ministry will ensure the grower(s) are informed they have clubroot (if they are not already aware), and are provided copies of the Saskatchewan Clubroot Management Plan, Clubroot Factsheet, and information on The Pest Control Act, and advise them what the next steps will be by the Ministry, SaskCanola and Municipality.

2. Producers and Producer Groups

  • Implement best management practices which adhere to the Saskatchewan Clubroot Management Plan.
  • Producer groups including the SaskCanola, the Saskatchewan Mustard Development Commission, the Saskatchewan Vegetable Growers Association and the Saskatchewan Seed Potato Growers' Association assist in educating Saskatchewan producers about clubroot prevention and management.
  • If clubroot is confirmed, SaskCanola will be informed and provide a news release following grower notification. The news release will disclose region but not specific area. The RM will determine how and when more specific information beyond the region will become public information.

3. Saskatchewan Association of Rural Municipalities (SARM).

  • Help educate Saskatchewan producers about clubroot prevention and management.
  • Rural municipalities have the authority under The Pest Control Act to undertake prevention and enforcement measures related to the spread and control of clubroot disease.
  • If clubroot is confirmed, SARM and the affected RM should be notified following grower notification.  The Ministry will work with the RM to develop a clubroot strategy and appropriate management plan, in reference to any relevant bylaws and extension materials and clubroot policies provided by SARM

4. Agricultural Retail Industry

  • Help educate the Saskatchewan agriculture industry about clubroot.
  • Take measures such as equipment cleaning to prevent the introduction and minimize the spread of clubroot from infested areas.

5. Equipment Dealers, Auctioneers and Custom Applicators

  • Help educate those purchasing equipment from infested areas (destined for Saskatchewan), as well as the custom application, seeding and harvesting industries about clubroot.
  • Take measures such as equipment cleaning to prevent the introduction and minimize the spread of clubroot from infested areas.

6. Oilfield, Gas, Road Construction and Other Companies Operating on Agricultural Land

  • Help educate the Saskatchewan oil, gas and other field operators about clubroot.
  • Take measures such as equipment cleaning to prevent the introduction and minimize the spread of clubroot from infested areas.

7. Saskatchewan Clubroot Initiative

  • Provide a forum to represent the interests and views of Saskatchewan's agricultural research and production sectors, producer and other industry groups and municipal government regarding the management of clubroot.
  • Provide consultation in the development of the Saskatchewan Clubroot Management Plan as well as evaluation and revision of the recommendations as required.
  • Help educate the Saskatchewan agriculture, equipment, oil, gas and other industries about clubroot and the economic and agronomic impacts the disease poses.

8. Researchers and Funding Agencies

  • Researchers should familiarize themselves with the Recommendations for Managing Risks Associated with Clubroot Research in Saskatchewan and use them to develop suitable measures for their unique research situation. Funding agencies should also be aware of these recommendations and may wish to consider the importance of containment protocols in research proposals when considering supporting clubroot projects in Saskatchewan.

References

Alberta Clubroot Management Plan, Alberta Clubroot Management Committee (revised May 2010) www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex11519

Best Management Practices: Clubroot Disease Management, Canadian Association of Petroleum Producers (July 2008)

Saskatchewan Clubroot Initiative

 Sean Miller (co-chair)
Saskatchewan Ministry of Agriculture
sean.miller@gov.sk.ca

Venkata Vakulabharanam (co-chair)
Saskatchewan Ministry of Agriculture
venkata.vakulabharanam@gov.sk.ca

John Ippolito
Saskatchewan Ministry of Agriculture
john.ippolito@gov.sk.ca

Shawn Senko
Canola Council of Canada
senkos@canolacouncil.org

Connie Achtymichuk
Saskatchewan Ministry of Agriculture
connie.achtymichuk@gov.sk.ca

Clint Jurke
Canola Council of Canada
jurkec@canolacouncil.org

Erin Campbell
Saskatchewan Ministry of Agriculture
erin.campbell@gov.sk.ca

Gary Peng
Agriculture and Agri-Food Canada
gary.peng@agr.gc.ca

Brent Flaten
Saskatchewan Ministry of Agriculture
brent.flaten@gov.sk.ca

Bruce Gossen
Agriculture and Agri-Food Canada
bruce.gossen@agr.gc.ca

Sherrilyn Phelps
Saskatchewan Ministry of Agriculture
sherrilyn.phelps@gov.sk.ca

Richard Gugel
Agriculture and Agri-Food Canada
richard.gugel@agr.gc.ca

Pat Flaten
SaskCanola
pflaten@saskcanola.com

Robin Morrall
University of Saskatchewan (retired)
robin.morrall@usask.ca

Laurel Feltin
Saskatchewan Association of Rural Municipalities
lfeltin@sarm.ca 

Paul Cawood
Canadian Association of Petroleum Producers
paul_cawood@nexeninc.com

John Meed
Saskatchewan Ministry of Highways
john.meed@gov.sk.ca

David Jessiman
Canadian Association of Agri-Retailers
david.jessiman@midwestagro.ca

Dan Steen
Saskatchewan Auctioneers Association
dsteen@rbauction.com

Gary Ericson
Saskatchewan Ministry of Energy and Resources
gary.ericson@gov.sk.ca

Barrie Jung
Saskatchewan Auctioneers Association
barrie@hodginsauctioneers.com

Tara Sample
SaskEnergy
tsample@saskenergy.com

Don Luthi
Saskatchewan Auctioneers Association
info@hodginsauctioneers.com

Ethan Sawchuk
SaskPower
esawchuk@saskpower.com

 

For more information, contact:
Saskatchewan Ministry of Agriculture
Agriculture Knowledge Centre
Toll Free: 1-866-457-2377
E-mail: aginfo@gov.sk.ca

 



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