Regular cleaning key to stopping spread of soil-borne threats.

We’re all in this together.

It’s a phrase Canadians from coast to coast have been using to show solidarity during the recent COVID-19 pandemic. It also sums up the approach many agricultural experts say growers and ag retailers need to take when it comes to limiting the spread of soil-borne pests.

Two of the most insidious threats to a growing number of Canadian producers are clubroot and the soybean cyst nematode (SCN). Clubroot is a soil-borne fungus that infects canola, causing roots to become deformed and making it difficult for the plant to absorb water and nutrients properly.

SCN has been present in North America since the 1950s and began spreading into Eastern Canada in the late 1980s. It is often referred to as the “hidden yield robber” and costs growers in Canada and the U.S. an estimated $1 billion each year.

We need to take an integrated approach to be successful.
Dan Orchard

While the threat of clubroot and SCN will likely never be completely eliminated, one agronomist says their impact can be significantly reduced by taking a united approach.

“Seed companies and life sciences companies are breeding resistant varieties. They’re really doing their part. What they always ask is that we use this in conjunction with other good management practices,” says Dan Orchard, an agronomy specialist with the Canola Council of Canada.

“We need to take an integrated approach to be successful. We say you need to take a ‘recipe’ approach. If you leave something out of your recipe you don’t get the desired final product,” he says. “Similarly, leaving out one of the management approaches may not control things to the level you are looking for.”

Although clubroot can be spread by wind and wildlife, experts say the most common form of transmission is via equipment moving from between fields, or even provinces. In one recent example, demo equipment from Alberta was directly linked to clubroot in at least one field in Saskatchewan.

Orchard’s advice to retailers and their customers is to guard against complacency: just because clubroot hasn’t been an issue on a farm in the past, don’t think it can’t be present now.

Clean it before you move it.

One of the most likely scenarios when it comes to spreading clubroot is when a piece of equipment is brought in from an area of high or unknown risk. In those cases, Orchard says it needs to be completely disinfected and properly sanitized.

There are generally three stages of sanitation. The first is a rough clean that essentially involves kicking off any loose soil that may be attached to the machine or its wheels.

“Level one can mitigate 90 or 95 percent of the problem because you can remove 90 or 95 percent of the soil by hand reasonably quickly,” Orchard says.

Stage two involves using compressed air or high-pressure water to remove whatever material you can’t by hand. The third stage is the use of a disinfectant such as bleach or a commercial cleaner, and is generally reserved for extreme situations where there is a very high likelihood of clubroot.

Such products are misted onto the equipment and allowed to saturate for 15 to 20 minutes.

Albert Tenuta, a field crop pathologist with the Ontario Ministry of Agriculture, Food and Rural Affairs, says that like clubroot, cleaning equipment between jobs remains the quickest and most effective way to limit the spread of the SCN, adding retailers and growers should pay particular attention to cleaning the wheels and undercarriage of any vehicles they use in the field.

Another consideration is the use of personal biosecurity measures. One such measure is wearing protective boot covers, which Orchard recommends when walking in a field where soil-borne threats may be present.

If boot covers aren’t an option, placing boots in a boot bath with bleach or other disinfectant will remove any spores or soil after a walk in the field. Any hand-held tools such as trowels, shovels or soil samplers should likewise be wiped clean or washed after they are used.

Carl Veikle, owner of Veikle Agro Inc. in Cut Knife, Sask., says clubroot has become a major concern for many of his customers in Northwestern Saskatchewan over the past three years. To help alleviate those concerns, his employees manually remove earth and disinfect the wheels on equipment before it is moved from one job site to another.

Still, Veikle says growers understand there is only so much that can be done to limit the spread of clubroot since there is a limited supply of time and resources. He says the best approach is to use common sense. “It’s just about being a little cleaner operation,” he says.

While cleanliness can go a long way in limited the spread of soil-borne pests and pathogens, Tenuta stresses that it’s also important for ag retailers and their customers to focus on early detection, which is one of the best ways to limit potential for spreading.

“You can’t put a wall around your field and keep soybean cyst nematodes or other things from coming in. What you can do is prepare for it. It starts with scouting and being able to know what to look for, whether it’s through digging up plants and looking at roots or taking a simple soil test,” he says.

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