Soybean School: To Till or Not to Till for White Mould Management?


It’s a disease that affects a number of significant crops in Canada, including vegetables, pulses, canola and even some forage species. And last year, some farmers saw particularly high levels of white mould in soybean crops across Ontario.

Soybean flower
White mould feeds off of soybean flower petals

Sclerotinia sclerotiorum, or white mold, makes its mark on plants in lesions that appear water-soaked; white, fluffy mycelium; and black sclerotia. The sclerotia overwinter, germinating again in the following year (under the right conditions). If spores are spread through rain or wind, and susceptible plants are hit, the disease can develop once again. But what made conditions in parts of Canada in 2014 so favourable to the development of white mold?

“Every year has some degree of white mold development,” says Albert Tenuta of the Ontario Ministry of Agriculture, Food and Rural Affairs. “The big difference in 2014…is the subsequent environmental conditions going into the main growing part of the season.”

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The cool, wet conditions allowed for more humidity, and less evapotranspiration, says Tenuta, creating good conditions for many leaf diseases, including white mold.

For those impacted by white mold in 2014, Tenuta encourages several practices to mitigate the risk of seeing the disease again this growing season. Growing non-host crops, less susceptible varieties, plants with good standability and lowering plant populations are a few ways to reduce that risk.

These are just a few of the things Bernard Tobin and Tenuta cover in this Soybean School, filmed at the SouthWest Agricultural Conference in Ontario. The duo also discuss the effect of soil tillage and fungicides on white mold. Take a listen.

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