A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases <http://www.isid.org>

Date: 5 September 2008
Source: Red Deer Advocate [edited]
<http://www.albertalocalnews.com/reddeeradvocate/news/Two_fields_infected_with_deadly_canola_disease.html>

Ponoka County has now found 2 fields contaminated with clubroot, a disease which ravages canola. Shayne Steffen, the county's manager of agriculture services, said the 2 fields are located east of Highway 2 and were identified during an ongoing inspection program. "We're still doing more surveying right now," said Steffen on Thursday [4 Sep 2008]. University of Alberta agriculture experts are also helping by doing pathology tests on the clubroot to identify what strain it is and perhaps provide clues to how it got to Central Alberta.

Steffen said a university expert was in the area on Wednesday [3 Sep 2008] to look at the infestations. The size of the areas of diseased crops suggested the spores that cause clubroot had likely been in the ground for up to 5 years. The infestations were found in the strips around the edges of the fields where farmers make their 1st passes with equipment. Clubroot infestations are typically found near the edges of fields and at entry points and the disease is often transported on farm equipment.

Eleven other Alberta counties have also confirmed the presence of the disease. Most are in the Edmonton area, where clubroot was first identified in a commercial canola operation in 2003. Lacombe County agriculture fieldman Dion Burlock said the inspections are ongoing but so far no further infestations have been found. Steffen said, "Quarantining the field is a good way to manage the infestation." He plans to continue his spot checks, but it is impossible to check all of the county's 700 000 acres [283 280 ha] of fields.

Clubroot is worrying for Canadian farmers because the type of canola grown in this country is particularly susceptible to the disease. It is a serious soil-borne disease that causes galls to form on canola roots, which ultimately causes premature death of the plant. There are no economical control measures that can remove the disease from a canola field once it has been infected. The best methods of preventing its spread are increasing canola crop rotations and ensuring farm equipment is cleaned before moving to a new field.

[Byline: Paul Cowley]

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Communicated by:
ProMED-mail
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[Clubroot of _Brassicaceae_ is caused by the fungus _Plasmodiophora brassicae_. It is a destructive soil-borne disease, which affects nearly all cultivated and many wild and weed members of this family, as well as some weed species in different families. The pathogen is found worldwide and is most damaging in temperate regions and tropical highlands. Symptoms on brassicas may include stunting and discoloured leaves as well as distortion and decay of roots. The fungus has a complex disease cycle and is spread with contaminated soil, plant material, water, and by human activities. Disease management is difficult due to the longevity of the spores and the inaccessibility of underground plant parts to fungicides. Numerous pathotypes exist, and this has hampered efforts to breed cultivars with durable resistance. For more information on the disease please see previous ProMED-mail post no. 20080509.1586 and links below.

Maps of Canada:
<http://www.lib.utexas.edu/maps/americas/canada_pol_1986.gif> and <http://healthmap.org/promed?v=55.4,-101.9,4>

Pictures
Clubroot symptoms on canola roots: ckick HERE
Cabbage with clubroot:
<http://vegetablemdonline.ppath.cornell.edu/PhotoPages/Crucifers/Clubroot/CruciferClubFS2.htm>
Cabbage field with clubroot symptoms:
<http://vegetablemdonline.ppath.cornell.edu/Images/Crucifers/Clubroot/Clbrt_Crucfs1.jpg>

Links
Additional news stories:
<http://cgi.bowesonline.com/pedro.php?id=23&x=story&xid=416818>,
<http://www.sunnysouthnews.com/index.php?option=com_content&task=view&id=920&Itemid=60>,
<http://www.vauxhalladvance.com/index.php?option=com_content&task=view&id=902&Itemid=1>,
and
<http://cgi.bowesonline.com/pedro.php?id=19&x=story&xid=415111>
Information on clubroot of canola:
<http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex8593?opendocument>,
<http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/faq7389?opendocument>,
and
<http://webpub2.strathcona.ab.ca/Strathcona/Rural+Life/Country+Talk/March+2006/Clubroot+disease+of+canola.htm>
Information on clubroot on crucifer crops:
<http://vegetablemdonline.ppath.cornell.edu/factsheets/Crucifers_Clubroot.htm>
Disease cycle of _P. brassicae_:
<http://vegetablemdonline.ppath.cornell.edu/PhotoPages/Crucifers/Clubroot/CruciferClubFS3.htm>
_P. brassicae_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=214750>. 
- Mod.DHA]