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Industry role in clubroot management

Photo by Leduc County.

Equipment, tools and footwear carrying clubroot-infested soil can easily spread this devastating canola disease from field to field. So preventing its spread is not a task just for farmers. Municipalities and companies that access agricultural land have important roles to play, too.

Clubroot is caused by a soil-borne pathogen that produces irregular swellings (galls) on the roots of canola and other cruciferous plants. The galls hinder the movement of water and nutrients into the top parts of the plant, resulting in major yield losses in susceptible canola cultivars. When the galls decay, they leave millions of resting spores in the soil that can survive for up to 20 years.

In 2003, clubroot was discovered in a canola field near Edmonton. Within a few years, the disease had become a very serious problem in Alberta canola, especially in the region around Edmonton. In 2007, the government of Alberta declared clubroot as a pest under its Agricultural Pests Act. The Act stipulates the municipality has the responsibility for enforcing pest control measures within its jurisdiction and the landowner/occupant is responsible for taking steps to prevent and control pests on his or her land.

Leduc County, located just south of Edmonton, has a clubroot policy that is about more than enforcement – it emphasizes working with producers to develop effective clubroot management strategies.

“Each year, Leduc County inspects every canola field in the municipality for the presence of clubroot. We usually start in the first week in July and continue until we get done,” explains Aaron Van Beers, agricultural foreman with Leduc County. He is responsible for the county’s Clubroot Inspection Program.

With about 700 to 900 canola fields to sample each year, the county has one seasonal employee dedicated to clubroot inspections, plus Van Beers helps out as he can. They usually sample in a field’s entry point; that’s the most likely spot for a clubroot infestation to start because contaminated equipment is the main way the disease is spread. Using a diamond pattern for sampling, they check the roots of 100 canola plants for galls.

“If we find any plants that have galling or what looks like galling, then we GPS mark that spot, and we send a sample to the lab to verify whether or not it’s clubroot. We also note how many plants out of 100 have galling on them,” says Van Beers.

“If the lab test is positive for clubroot, then we inform the landowner and also the renter, if we know who the renter is. If less than 30 out of the 100 plants have galling, we don’t issue a notice. However, we strongly recommend using clubroot-resistant canola varieties, stretching the crop rotation as long as possible, and cleaning the field equipment – doing what you can to mitigate your clubroot risk.”

If 30 or more of the 100 plants have galls, then the inspection staff return to the field after harvest to do a more thorough survey to see if the high infestation level occurs throughout the field or is perhaps just an isolated patch in the initial sampling area.

“If clubroot is at a high level consistently across the whole field, then we issue a notice based on clubroot being a declared pest under Alberta’s Agricultural Pests Act,” explains Van Beers. The notice specifies the clubroot control actions that must be taken on that field.

He says, “We really want to make sure that growers are mitigating their risk, so the most important control measures are: crop rotation, using clubroot-resistant varieties and rotating those resistant varieties. Our notice stipulates they cannot grow canola on that field for three years. In the fourth year, they may grow canola but it must be a clubroot-resistant variety. By the fourth year, there will probably be new canola varieties and maybe there will be new resistances available.”

Clubroot-resistant cultivars are the foundation of clubroot management in canola. However, if the same resistant cultivar is grown back-to-back or in very short rotations, the risk is high that the pathogen will adapt and overcome the cultivar’s resistance.

Although Leduc County’s inspection program won’t necessarily catch every occurrence of clubroot in the county, the sampling results do provide a springboard for county staff to work one-on-one with producers who are having clubroot problems.

“Our producers have been dealing with clubroot since 2007, so the vast majority of them are aware of the disease and are managing the disease. For those few who maybe don’t know what clubroot is, we make sure they are aware of the risks they are running, help them to minimize those risks and then to stay vigilant,” says Van Beers. “The long-term issue is to protect our clubroot resistances so that we don’t get resistance breakdown. Researchers have already found a new clubroot pathotype [in the Edmonton region] that the current clubroot-resistant canola varieties are susceptible to.

“That’s a huge warning bell in my books,” he adds. “So we’re really trying to make sure we don’t have that situation come up here. If it does, then we’re back to square one, and canola crops will be devastated until we get new resistant varieties.”

As you would expect, Leduc County’s clubroot inspection protocols also ensure staff don’t spread the disease. “Our vehicle doesn’t enter the field; we park on the side of the road. And we try to minimize how much we enter the field as much as possible – that’s another reason why we stick to the field approaches,” explains Van Beers. “When we enter the field we put on disposable boot covers and nitrile gloves. We use hand pulling, not shovels, to sample the plants so we don’t have the potential for cross-contamination from soil on a shovel. When we come out of the field, we discard the boot covers and gloves in a garbage bag for disposal later.”

Other players
The government of Alberta’s Clubroot Management Plan lays out the clubroot management responsibilities of the provincial government, municipal governments, landowners/occupants, agricultural retail and service industry businesses, and energy, construction and transportation companies that operate on agricultural land.

One company that sometimes needs to access agricultural land is ATCO Electric. “For ATCO Electric Distribution, most of our lines are built along road right-of-ways; however there are some circumstances that may warrant construction through an agricultural field, and we also have existing infrastructure that was routed through a field. In those cases we would need to access the agricultural lands during construction, certain maintenance activities and emergency events to restore power,” explains Bettina Mueller, environment manager with ATCO Electric’s Distribution Division.

Managing clubroot is important to ATCO Electric for several reasons. She says, “We realize that clubroot is a serious disease that can affect canola and the entire cabbage family, and also in 2007 clubroot was declared an agricultural pest in Alberta. So we recognize the detrimental effects it can have on crop yields.”

ATCO Electric has internal best management practices that include direction for the company’s field staff on agricultural pest issues such as noxious weeds and clubroot. To develop its clubroot practices, ATCO Electric reviewed the Alberta Clubroot Management Plan and talked with staff at Alberta Agriculture and Rural Development, and also reviewed some other agencies’ best management practices. In addition, Mueller and some of her colleagues attended the International Clubroot Workshop held in Edmonton in 2013 for the latest information on this issue.

Talking with the landowner is also key to how ATCO Electric approaches clubroot management. “As part of any access to land, of course, we have a conversation with the landowner prior to entering the land, and part of that conversation is to discuss the status of the fields and if any precautions need to be taken,” says Mueller.

The company’s best practices include, where possible, scheduling construction work for when the ground is dry or frozen, to reduce the chance of getting soil on equipment and tools. The best practices also identify three possible levels of cleaning, ranging from mechanical cleaning, to washing, to disinfecting, depending on the situation.

ATCO Electric’s standard practice is to arrive onsite with clean equipment, which has been mechanically cleaned with brushes, brooms and so on to remove dust, soil and plant materials. “However, especially when we know that we’re working in clubroot-infested areas, we have that conversation with the landowner, and the cleaning level is then decided based on consultation with the landowner and sometimes the agricultural fieldmen may get involved and/or a municipality may have its own [requirements],” notes Mueller. The Alberta Clubroot Management Plan specifies a standard for clubroot control measures for all Alberta municipalities, but individual municipalities can choose to enhance that standard within their own jurisdiction.

ATCO Electric is willing to work with landowners to provide assurance that the company’s equipment is clean. Mueller says, “It’s based on the discussions that we have with the particular landowner. Some might say, ‘I would like the level one cleaning; just make sure it happens.’ Others might say, ‘I would like to see the equipment before it goes on my field.’ We try and accommodate the landowner as best as we can.”

Van Beers emphasizes the importance of having these types of conversations whenever any company or business will be accessing your agricultural land.

“The main thing is to talk with the company before they enter your land, to have it all on the table. You can set out what you feel are your requirements for them to adhere to and you can ask them what are their protocols for clubroot, or blackleg, or weeds, or any other issue that you might have. So you could ask them: How are they going to ensure that they’re not bringing clubroot from somewhere else? What level of equipment cleaning will they do? How will they ensure that level of cleaning is actually done? And so on. That way you’re both clear about what is expected and what isn’t,” says Van Beers.

“Having that conversation goes a long way to nipping any issues in the bud.”

January 16, 2015  By Carolyn King