Shorter clubroot rotation OK: Sask.

Saskatchewan Agriculture continues to recommend that the province’s canola growers follow a one-in-four-year rotation.

However, the province and other industry groups say a one-in-three-year canola rotation is acceptable in cases where visible clubroot symptoms are evident.

On the surface, that might seem like the province is preaching one thing and practicing another.

However, officials from the provincial ag ministry say that’s not necessarily the case.

The one-in-four-year rotation is a general recommendation for canola that covers all diseases, according to the ministry.

The one-in-three-year rotation is specific to clubroot and is the minimum required rotation in cases where clubroot has been confirmed.

Barb Ziesman, provincial plant disease expert with Saskatchewan Agriculture, says the three-year minimum required rotation for clubroot-infected fields is based on science that shows a two-year interval between canola crops can help to reduce clubroot spore loads significantly.

“All of our recommendation are based on science,” Ziesman said.

“In a typical situation (where clubroot is found), the absolute minimum is a three-year rotation, but if the spore loads are high enough and the producer is concerned, then there are benefits in extending that rotation beyond three years.…

“The four-year recommended rotation is consistent with best management practices for canola when you look at overall agronomy and disease management.”

Beginning this year, Saskatchewan is expanding its provincial clubroot survey and will require growers to develop a formal clubroot management plan if visible symptoms of the disease are detected in their fields.

One of the minimum requirements of getting a clubroot management plan approved is a commitment by the grower to produce canola no more than once every three years on infected land.

In other words, management plans are not required to conform with provincial recommendations.

Does that mean the province is ignoring its own advice?

Not really, say Ziesman.

The management plan requirements were developed in consultation with disease researchers who work with clubroot and are familiar with how the pathogen spreads.

Organizations that were involved in developing the minimum requirements considered the science that was available and felt that a two-year break between canola crops was sufficient on land that shows visible symptoms of the disease, she said.

Clubroot management plan guidelines were developed in consultation with SaskCanola and canola researchers, as well as the Saskatchewan Clubroot Initiative, a ministry- led group that includes representatives from Agriculture Canada, SaskCanola, the Canola Council of Canada and other industry groups, including crown utility companies.

When asked if the risk of clubroot infection is lower in a four-year rotation than a three-year rotation, Ziesman said researchers are looking into it.

brian.cross@producer.com

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