Grey Stem disease is widespread throughout western Canada. Grey Stem will generally infect too late in the growing season to cause significant yield loss.

How do I Know if its Blackleg or Grey Stem?

To differentiate Blackleg and Grey Stem at the end of the season, cut the lower stem and look for dead blackened tissue in the crown. This blackened tissue is characteristic of Blackleg, not Grey Stem.                                       

What to Look For

Grey Stem causes grey, silvery or purplish patches to develop on the stem of canola. These patches can cover whole stems and continue to spread into stubble as the plant decomposes.

   Grey Stem     Grey Stem

                Grey Stem                                  Grey Stem versus Blackleg


There are many measures you can take to prevent the spread of Grey Stem:

  • Practice proper rotation of canola crops;
  • Control all cruciferous weeds including volunteer canola; and
  • Reduce stress from competition by using good fertility practices.

Related Links

Canola Council of Canada Grey Stem