Clubroot appeared in 24 more Saskatchewan fields in 2020, according to the map released Jan. 11.
Visible disease has now been confirmed in 75 canola fields since 2017.
Also last year, the pathogen was detected in another 18 fields that didn’t have symptoms, for a total of 29.
Provincial plant disease specialist Alireza Akhavan said Saskatchewan is in a much better position than Alberta, where more than 3,000 fields are infected, to control the disease as long as growers manage properly.
“The pathogen itself may be present in many more fields, but with low populations so producers perhaps do not observe symptoms, but they should consider that if an RM (rural municipality) or a neighbouring RM has clubroot they also perhaps have the clubroot pathogen in their soil in low numbers,” he said. “They should take management and due diligence to have it in the low numbers, to not let it get to the population needed to produce the galls.”
Rotation is still key to control.
Akhavan said a three-year break from canola is ideal. Some producers are growing in tighter rotations than that and some are still growing canola back-to-back despite the clubroot risk.
As soon as the pathogen is present in sufficient amounts to develop the galls it becomes difficult to manage, he said.
Because the spores can spread through wind and soil movement, on equipment and on shoes, the extended rotation can help keep their numbers low.
The 2020 clubroot survey examined 474 fields in high-risk areas, 261 through a general crop survey and 231 through voluntary on-farm testing.
The provincial agriculture ministry and SaskCanola collaborated on the voluntary program, in which growers were given soil-testing bags they could fill and return for testing. Akhavan said 1,300 bags were prepared but only 231 returned.
Part of the problem was the lack of events such as farm shows due to the COVID-19 restrictions but he said producers could still get the bags from grower organizations.
Of the 231 samples submitted and sent to Discovery Seed Labs for testing, 11 returned positive results.
Akhavan noted this project is still under evaluation but he would like to see more on-farm participation in 2021. It’s a way to find those low-level fields and prevent the disease from taking hold.
He also said growing clubroot-resistant varieties is a good practice but not enough on its own. Even with a resistant variety he recommends a four-year rotation.
Producers should also be cautious when allowing equipment on their fields. Purchasing seed potatoes and hay from areas where clubroot is a problem is also discouraged.
All landowners of the 966 fields checked in 2020 have been contacted and the field locations shared with the rural municipalities if they have a clubroot bylaw.
Clubroot is a pest under provincial legislation.