Third Sask. field joins clubroot club

Saskatchewan’s canola growers have been warned to seed with care as a canola field in west-central Saskatchewan has been confirmed as the third in the province to have clubroot.

SaskCanola, the province’s canola development commission, announced Tuesday it had received confirmation from the provincial ag ministry of the new finding, discovered during an annual survey of 91 canola field soil samples taken last year.

“In response to this finding, stakeholders are implementing the protocols laid out in the Saskatchewan Clubroot Management Plan,” said Franck Groeneweg, the commission’s vice-chairman and a canola grower at Edgeley, northeast of Regina.

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Clubroot is established in some vegetable-growing regions elsewhere in Canada, but didn’t turn up in Prairie canola until arriving in fields near Edmonton in 2003 — and has since been confirmed in one or more fields in over 20 Alberta municipalities.

The disease was first confirmed in Saskatchewan in a pair of fields in the north-central crop-growing region in 2011. Levels of clubroot capable of producing disease have since also been found in two soil samples that were collected from Manitoba canola fields last year.

Soil samples from another west-central Saskatchewan field had also previously turned up positive for the clubroot pathogen, in 2009. However, confirmation of clubroot requires detection not only of the pathogen’s DNA in a plant or soil sample, but of disease symptoms in a susceptible plant.

The two fields in Saskatchewan’s north-central cases had shown no above-ground symptoms and could possibly have sat undetected indefinitely if the fields hadn’t also been seed trial sites for Cargill. Scientists with the agrifood company had pulled up some trial plants as part of a routine whole-plant observation.

The soil-borne pathogen that causes clubroot creates deformed roots in canola and other brassica plants, and thus might sit in the soil for up to 20 years, undetected until the galls formed on the roots interfere with the plants’ water and nutrient uptake. Clubroot galls can cut an infected plant’s yield by about 25 per cent on average.

“In order to protect this crop as a rotation mainstay, we as growers must engage in best farming practices to help prevent the spread of this soil-borne disease,” Groeneweg said Tuesday.

For other growers, the commission said, that means working to reduce the spread of the disease and reduce the severity of the disease when it’s found.

To cut the spread of clubroot, growers need to remove soil from field equipment coming from infected areas, the commission said.

Reducing the severity of clubroot means scouting for root symptoms to catch it early, giving farmers more options for managing it, the commission added.

Growers aiming to cut the disease’s severity also need to use disease-resistant varieties, plan out a four-year crop rotation in order to limit the growth of the root galls, and use “effective weed management.”

Related stories:
Clubroot found in Manitoba soils, March 1, 2013
Three more Alta. counties join clubroot club, Oct. 4, 2012
Sask. won’t ban canola from fields with clubroot, Oct. 7, 2011
Clubroot-resistant RR canola registered, April 9, 2009

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