A cool, wet summer has left many Ontario soybean fields with some level of white mould infection. The fuzzy white stem rot could be seen in patches across many fields by late summer, sometimes causing large areas of loss in a field. A key element of controlling or avoiding this disease is understanding how it grows, spreads and infects soybeans.
The white mould is a fungus which creates a small, hard, black structure called a sclerotia body — these can be found in the stems of infected soybean plants. As Shawn Brenneman, Syngenta’s agronomic services manager for eastern Canada, explains in this Soybean School, these fruiting bodies can persist up to 10 years in the soil, waiting for another year of good conditions to germinate and spread.
But while sclerotia can live for years, they can really only germinate at or near the soil surface. In the video below, Brenneman runs through the fall or spring tillage you may want to do if you plan on putting a particular field back to soybeans, and explains why moving to a no-till wheat (or other crop) situation may be the best bet in areas of high pressure.
Brenneman also covers the role variety selection, row spacing and plant population have on total crop risk of the disease, and why, if weather conditions set up to favour the disease again, a fungicide application must go on quite early and possibly more than once.