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Clubroot on oilseed rape in Saskatchewan, Canada


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 10 Jan 2022
Source: Global News [summ. Mod.DHA, edited]
https://globalnews.ca/news/8500409/clubroot-canola-saskatchewan-2/


Clubroot was first detected in Saskatchewan in 2008. The number of canola fields with clubroot increased during 2021. Visible symptoms of clubroot were identified in 5 commercial fields during the year [2021], bringing the total to 80 since 2017. The pathogen DNA was detected in soil samples from 9 fields, for a total of 38 fields in the province. Results are compiled annually through surveys, reports and samples.

Early detection, tracking, and managing clubroot protects producers. In 2021, more than 750 fields in 200 rural municipalities were examined. Owners of fields with visible clubroot symptoms or presence of pathogen DNA were contacted. Producers are encouraged to continue to submit soil samples for testing, with 100 samples sent in for testing during 2021. The goal is to detect the pathogen when spore levels are low. Use of clubroot-resistant canola varieties with a minimum 3-year crop rotation is recommended to help minimize yield loss while protecting the effectiveness of clubroot-resistant varieties.

[Byline: David Giles]

--
Communicated by:
ProMED

[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, turnips, 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 through 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 post 20120521.1139354).

The species is composed of numerous pathotypes, which makes breeding crop cultivars with durable resistance difficult. It is therefore important to use multiple approaches to disease management simultaneously to counteract pathogen adaptation and extend the useful duration of both host resistances and effectiveness of fungicides.

In Canada, several new pathotypes leading to host resistance breakdowns have been reported previously from western areas (ProMED posts 20210318.8255944, 20180503.5780419 and see links below).

Maps

Canada (with provinces):
http://mapsof.net/uploads/static-maps/Canada_Provinces_and_territories_map.png

Pictures

Clubroot symptoms on roots of oilseed rape:
https://www.realagriculture.com/wp-content/uploads/2012/08/club-root.jpg and
https://www.agric.wa.gov.au/sites/gateway/files/styles/original/public/Club%20root.JPG
Clubroot-affected oilseed rape plants:
http://www.canolawatch.org/wp-content/uploads/2013/04/Clubroot-rotation-effect-cont.-canola.jpg (resistant vs. sensitive cultivars)
Clubroot symptoms on other brassica crops:
https://pnwhandbooks.org/sites/pnwhandbooks/files/plant/images/broccoli-brassica-oleracea-clubroot/broccolitransplantclubroot.jpg,
https://c8.alamy.com/comp/BG75EM/clubroot-plasmodiophora-brassica-distorted-root-on-a-cabbage-plant-BG75EM.jpg and
http://www.omafra.gov.on.ca/IPM/images/brassica/diseases/clubroot_brussels_zoom.jpg (affected field)

Links

Additional news story:
https://leaderpost.com/news/canola-disease-continues-spread-in-saskatchewan
Information on clubroot of oilseed rape:
http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex8593?opendocument,
http://www.canolawatch.org/2013/04/04/rotations-role-in-clubroot-management/,
https://www.canolacouncil.org/canola-encyclopedia/diseases/clubroot/,
https://bit.ly/38SXxBC and
https://doi.org/10.1111/ppa.12949 (crop rotation)
Information on clubroot on crucifer crops:
https://www.agric.wa.gov.au/broccoli/managing-clubroot-vegetable-brassica-crops,
https://ag.umass.edu/vegetable/fact-sheets/brassicas-club-root,
https://cropscience.bayer.co.uk/threats/diseases/field-brassica-diseases/clubroot-brassicas/,
http://vegetablemdonline.ppath.cornell.edu/factsheets/Crucifers_Clubroot.htm and
https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/em9148.pdf
Clubroot disease cycle:
https://www.gov.mb.ca/agriculture/crops/plant-diseases/images/fac63s00a_sm.jpg
Clubroot pathotypes & previous surveys in Canada:
https://bit.ly/38VwZ2I,
https://bit.ly/2ODvRdn and
https://globalnews.ca/news/7568958/clubroot-saskatchewan-agriculture-saskcanola-canola/
_P. brassicae_ taxonomy:
http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=214750
- Mod.DHA

ProMED map:
Saskatchewan Province, Canada: https://promedmail.org/promed-post?place=8700859,262]

See Also

2021
----
Clubroot, oilseed rape - Canada: new strains 20210318.8255944
2019
----
Clubroot, oilseed rape - Canada: (MB) 20190916.6677882
2018
----
Clubroot, oilseed rape - Canada: host resistance break down 20180503.5780419
2017
----
Clubroot, oilseed rape - Canada: (ON) 20170115.4767978
2015
----
Clubroot, oilseed rape - Canada: (MB) 20151023.3737088
Clubroot, oilseed rape - Canada: new strain (AB) 20150618.3447106
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
2008
----
Brassica diseases - Turkey, Nepal 20080213.0572
and additional items in the archives

 



More news from: ISID (International Society for Infectious Diseases)


Website: http://www.isid.org

Published: January 14, 2022

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