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Cleaning for clubroot

Researchers agree that the most effective way to control the spread of clubroot is to sanitize machinery. This is effective, but time consuming

While there is no foolproof way to prevent clubroot from getting into your fields, sanitizing equipment is one way to prevent its spread.

Dr. Stephen Srelkov, plant pathologist at the University of Alberta told delegates at the 2013 International Clubroot Workshop in Edmonton that “the largest risk comes from the movement of equipment.”

Moving dust and water can also spread microscopic clubroot spores. Besides moving to zero tillage, there isn’t a lot that farmers can do to prevent this type of spread.

Seeds and tubers can spread the disease, Stelkov says. “Farmers should avoid the planting of common untreated seed harvested from clubroot infested fields.”

Effective cleaning

Since moving equipment accounts for the largest risk of the spread of clubroot, it makes sense for farmers to consider sanitizing equipment as they move from field to field. This is especially true if you believe clubroot is established in one field in your operation.

The Canola Council of Canada recommends a three-step process to equipment sanitization. More information can be found online on the Canola Council of Canada website at www.clubroot.ca.

Step 1: Rough cleaning This step should remove about 90 per cent of soil from the unit. Use a hand scraper, a wire brush or an air compressor to remove dirt. For a 40-foot cultivator, the Canola Council estimates this may take one to two hours.

Step 2: Fine cleaning Use a pressure washer at 2,000 to 3,000 p.s.i. everywhere dust, soil and crop debris could accumulate. Step 1 and Step 2 combined should remove 99 per cent of soil from the unit. The Canola Council estimates that this may take another one to two hours for a 40-foot cultivator.

Step 3: Disinfection The Canola Council recommends using a backpack sprayer to apply a one per cent bleach solution or a commercial surface disinfectant. You will need to ensure that the area remains wet with the solution for 15 to 20 minutes. Applying disinfectant in early morning or early evening will reduce evaporation, keeping the area wet for a longer time. This can take two hours or more for a 40-foot cultivator.

Barriers to sanitizing

Once clubroot spreads to a field, it is very difficult to eradicate. It is easy to see how clubroot spores could move from field to field on equipment. However, there are practical reasons that all farmers haven’t adopted a strict on-farm equipment sanitation policy.

  • Practical details: Once you’ve cleaned your machine, where can you safely put the infected dirt? It’s important to make sure that the infected dirt and the water you use to clean the machine don’t wind up in an area where they can infect a field or re-infect the machine later. If you decide to clean in-field, how will you get water and a pressure washer to the site?
  • Disinfectant: Some disinfectants can be harmful to humans. Bleach can corrode equipment, especially tires.
  • Time: Thorough cleaning can take quite a bit of time. As shown in the above example, the Canola Council of Canada estimates that it would take four to six hours or more to effectively clean a 40-foot cultivator. Cleaning the last speck of dust out of a combine after finishing each field would be very time consuming. And don’t forget the quad used to check a field, the grain truck, and the half-ton truck.
  • It’s not a guarantee: You could thoroughly clean your equipment, then drive through lumps of mud from your neighbour’s tractor on the road. If there are clubroot spores in that soil, you’ll have it on your tires even after all your efforts. There is nothing you can do to stop clubroot’s spread through dust or water.

It’s important to come up with a policy that makes sense for your farm, your location and your level of risk tolerance.

Living with clubroot

Alberta consultant Paul Muyres has been working with clubroot infected fields since 2007. At that time, Muyres says, “there was a lot of fear.”

When farmers found clubroot in their fields, “there was just no alternatives.”

To help ease his clients’ minds, he developed a 16-item protocol list for cleaning equipment.

He cleaned his truck from field to field, including using disinfectant. “I went through tires because the bleach erodes the rubber.”

He found that this cleaning regime really ate into his time. “In an eight-hour day of scouting fields, I had four more hours [of cleaning] attached to that.”

Now, Muyres finds that most of his clients who have found clubroot in one field assume that they have it in all of their fields. Now, he treats each clients’ fields as one operation. He still cleans all of his equipment between clients, but he doesn’t clean from field to field. “It’s clean in, clean out.”

These days, he says, his clients “aren’t going to lose their minds about the fact that they have clubroot. We have to simplify our lives when it comes to being out in the field.”

“Clubroot is where blackleg was when we first started growing canola,” Muyres said. “Think about where we’ve come.” Clubroot was found in Alberta in 2007, and “by 2010, we had resistant varieties.”

“Farmers just assume they have the disease in the world that I live in,” Muyres says. “They grow clubroot varieties. End of story.”

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