OMAFRA Report: Snow mould in Ontario winter wheat fields

A weekly report prepared by the staff of the Ministry of Agriculture, Food and Rural Affairs (OMAFRA).  If you require further information, regarding this report, call the Elora Resource Centre at 519-846-0941.  Office hours: 8:30 a.m. to 4:30 p.m. 

For technical information, call the Agricultural Information Contact Centre at 1-877-424-1300 or visit the OMAFRA website:


When/where does it occur? 

Snow mould occurs in areas with significant snow cover on ground that doesn’t freeze or freeze deeply enough prior to the snowfall.  

The snow provides insulation for the fungal pathogens that can survive in soil and on residue, and allows them to grow on plants throughout the winter. After snow has melted, damp and cool weather is conducive for continued growth of the pathogens damaging the plants further.

What does it look like?

Symptoms are typically patchy and appear after the snow melts in the spring.  In the case of severe infection, the growing point can be damaged eventually causing the plants to die. 

There are various types of snow mould that can occur including pink snow mould and speckled snow mould. 

In fields infected with pink snow mould, plants will turn pink, while fields with speckled snow mould will look gray. The fungal growth can be seen right after the snow has melted and within a few days will appeared speckled from dark fungal structures that form on leaves.

What losses can I expect? 

In cases where infection does not damage the growing point, the plants should grow out of it as temperatures rise and plants continue to develop. In these situations, the impact on yield should be minimal. However, in cases of severe infection, the growing point may be damaged, and the plants will die. 

It is important in those fields to do an assessment once green up has occurred to get a handle on the impact across the entire field. Disease is generally sporadic and is found in patches throughout the field. 

When making assessments it is important to conduct a stand count in various parts of the field in order to determine the best course of action moving forward.

If plant stems/crowns are “mushy” those plants are unlikely to survive, while stems that are firm but have diseased/dead leaves generally survive well. Looking for new white root growth is another early indicator.

Joanna Follings