Nothing fancy about killing clubroot

An Alberta study has shown that household bleach works as well as specialized disinfectants

Glacier FarmMedia – A jug of household bleach is an important tool in the fight against clubroot.

Studies by Alberta Agriculture crop pathologist Michael Harding, which compared different disinfectants that can be used to sanitize farm equipment, showed a 50:50 concentration of common household bleach and water killed spores and is cheaper than other options.

A few years ago, Virkon disinfectant was among those recommended for washing farm equipment to prevent the spread of clubroot from field to field.

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“Virkon is not as effective as originally thought,” said Canola Council of Canada agronomy specialist Autumn Barnes.

“Bleach is quite affordable and a really good option. We know it works and we know it works quickly, so that’s what our recommendations are. None of us agronomists use Virkon and are recommending that people do not use Virkon for equipment sanitation.”

Clubroot has been confirmed in Ontario canola fields where it is now becoming a challenge. The disease is transferred in soil so equipment sanitation has been one of the suggested ways to control movement of the disease from field to field, but it is not that practical to have farmers clean equipment between every field.

The Alberta Agriculture study compared results from nine commercial disinfectants and three other unidentified products not on the market. Four of them achieved 95 per cent kill on clubroot spores, but bleach is the lowest cost and the easiest to obtain.

Barnes said a mist of the bleach solution is a good step toward controlling spore spread. However, it does lose effectiveness over time, once opened.

“If you’re not going to be using a lot of it, don’t go buy some discount vat of bleach,” she said.

Crop rotation, with at least two years without a host crop, is one way to reduce risk. Hosts include not only canola but also volunteer canola, mustard, wild mustard, stinkweed and shepherd’s purse, so weed control is important.

Soil movement between fields should be minimized, and if clubroot is anywhere near the area, farmers are encouraged to grow resistant canola varieties, Barnes said.

“It’s not free and it’s not easy to bring in resistant genes, and there’s not an indefinite number of them, so we need to be really respectful of the genetics that we’ve got.”

Soil can be tested for spores, but the best way to identify the disease is to scout fields during the growing season and examine the roots of canola plants. Barnes advised paying particular attention to field entrances and exits, areas near grain bins and bags, beehive site entrances, lower areas, weedy areas and patches of crop that are prematurely ripe.

If galls are found on plant roots, growers should first obtain lab confirmation and then figure out their next moves.

Reporting the finding can help manage spread and help in the allocation of resistant seed varieties.

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Reporter/Glacier FarmMedia staff

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