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: Mon 15 Jun 2015
Source: Canadian Manufacturing, The Canadian Press report [edited] <http://www.canadianmanufacturing.com/supply-chain/albertas-canola-sector-hit-by-clubroot-epidemic-149860/>
Alberta's canola hit by clubroot epidemic
A tough new strain of clubroot was detected by a University of Alberta researcher. Clubroot was first discovered in Western Canada in 2003.
Since then the soil-borne pathogen has steadily moved from a few fields to 30 municipalities.
New varieties of canola have been developed that can resist clubroot, but last year [2014] a newer strain of the disease was detected.
"There are 16 fields confirmed in Alberta with a strain of clubroot that has overcome all of our resistant varieties that are currently on the market," said Dan Orchard, Canola Council of Canada.
Low concentrations of regular clubroot strains have been found in Saskatchewan and Manitoba, but not the newer strain. The disease has not had a major effect on crop yields so far.
Orchard said the industry wants to ensure that it continues by preventing all forms of clubroot from spreading into new growing areas. To that end, researchers are working to develop even tougher types of canola. In the meantime, growers are being encouraged to plant the latest clubroot-resistant varieties before the disease shows up.
The industry is also encouraging producers to extend crop rotations and to clean and disinfect machinery used in one field before moving to another. Orchard said growers in Saskatchewan and Manitoba could be spared what is happening in Alberta if they follow those steps.
"Alberta had to learn the hard way."
[Byline: John Cotter]
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Communicated by: ProMED-mail <promed@promedmail.org>
[Clubroot of _Brassicaceae_ is caused by the fungus-like organism _Plasmodiophora brassicae_. It is a destructive soil-borne disease affecting nearly all cultivated members of the family, including oilseed rape (_Brassica napus_; "canola" refers to a group of specific varieties), cabbages and turnip, as well as many wild species which may serve as pathogen reservoirs. It is found worldwide and is most damaging in temperate regions and tropical highlands.
The pathogen enters root hairs and wounded roots. It multiplies rapidly causing abnormal enlargement of the underground stem, taproot or secondary roots ("clubs"). Affected roots often decay before the crop has matured. Depending on the timing of infection in the crop cycle, symptoms may include wilting, stunting, and yellowing of plants, or premature ripening resulting in shriveled seeds. Due to the distortion of the roots, plants may wilt in dry weather and then recover at night.
Decaying roots release many resting spores, which can survive in the soil for a decade or more in the absence of a susceptible host plant.
The disease can be spread with soil (for example on agricultural machinery), farming activities and infected plant debris. Use of clean planting material and phytosanitary measures to prevent spread between fields is essential. Disease management is difficult due to the longevity of the spores and the inaccessibility of underground plant parts to fungicides. Raising soil pH by addition of lime and experimental fumigation treatments have been shown to be effective (see ProMED-mail post 20120521.1139354).
The species is composed of numerous pathotypes, and several of them are known to occur in Alberta (see link below). This makes breeding crop cultivars with durable resistance difficult, which is illustrated by the emergence of a new resistance-breaking strain reported above.
Maps
Canada:
<http://www.lib.utexas.edu/maps/americas/canada_pol_1986.gif> and <http://healthmap.org/promed/p/263>
Alberta:
<http://www.canmorealberta.com/images/maps/alberta_map.jpg>
Pictures
Clubroot affected oilseed rape plants:
<http://ws373847.websoon.com/images/uploads/figure_2_lg.JPG> and <http://www.canolawatch.org/wp-content/uploads/2013/04/Clubroot-rotation-effect-cont.-canola.jpg>
(resistant vs. sensitive cultivars)
Clubroot symptoms on roots of oilseed rape:
<https://www.realagriculture.com/wp-content/uploads/2012/08/club-root.jpg>,
<https://www.pioneer.com/CMRoot/pioneer/canada_en/images/clubroot_susceptible.jpg>,
and
<https://www.agric.wa.gov.au/sites/gateway/files/styles/original/public/Club%20root.JPG?itok=BCml2AwN>
Clubroot affected rape field:
<http://archive.canola-council.org/clubroot/images/figures/Figure_13_lg.jpg>
Clubroot symptoms on cabbage:
<http://vegetablemdonline.ppath.cornell.edu/PhotoPages/Crucifers/Clubroot/CruciferClubFS2.htm>
and
<http://vegetablemdonline.ppath.cornell.edu/Images/Crucifers/Clubroot/Clbrt_Crucfs1.jpg>
(affected field)
Links
Story also available at:
<http://winnipeg.ctvnews.ca/canola-industry-encouraging-growers-to-plant-clubroot-resistant-varieties-1.2422081>
Information on clubroot of oilseed rape:
<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://archive.canola-council.org/clubroot/about_clubroot.aspx>
Benefit of crop rotation for clubroot management:
<http://www.canolawatch.org/2013/04/04/rotations-role-in-clubroot-management/>
Clubroot pathotypes in Alberta:
<http://www.seed.ab.ca/pdf/ClubrootCanola.pdf>
Information on clubroot on crucifer crops:
<http://vegetablemdonline.ppath.cornell.edu/factsheets/Crucifers_Clubroot.htm>
Disease cycle of _P. brassicae_:
<http://archive.canola-council.org/clubroot/images/figures/Figure_2.gif>
_P. brassicae_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=214750>
and via
<http://tolweb.org/Plasmodiophorida/121506>
- Mod.DHA]
[See Also:
2012
----
Clubroot, oilseed rape - Australia: 1st rep. (WA) 20120521.1139354 Clubroot, oilseed rape - Canada: (MB) 20120502.0994
2011
----
Clubroot, oilseed rape - Canada: (SK) 20111007.3012
2010
----
Clubroot, oilseed rape - Canada: (AB), spread 20100118.0206
2008
----
Clubroot, canola - Canada (02): (AB) 20080916.2899 Clubroot, canola - Canada (SK): alert 20080509.1586 Fungal diseases, oilseed rape - UK, Canada 20080407.1272 Brassica diseases - Turkey, Nepal 20080213.0572
2007
----
Clubroot, canola - Canada (AB) 20070927.3199
2005
----
Clubroot, canola - Canada (AB) (02) 20051113.3319 Clubroot, canola - Canada (Alberta) 20050512.1301]
Topics
Species
