Fusarium graminearum, which was first detected in western Canada in 1984 along Manitoba's Red River Valley, produces deoxynivalenol or DON, a mycotoxin, which lowers the end-use quality of the grain.

Canadian Grain Commission mycologist, Tom Graefenhan, says until 1998 the 15-A DON chemotype was the predominant type in Manitoba but since then it's been partly replaced by the 3-A DON chemotype which produces more of the DON mycotoxin.

Tom Graefenhan-Canadian Grain Commission

Over the last 10 years, we have seen an increase in the occurrence of the 3-A DON chemotype and in 2008, at least 70 per cent of the Fusarium graminearum population consisted of the new chemotype in Manitoba.

In Saskatchewan it is about 30 per cent and we can observe a similar trend in Minnesota and North Dakota as well.

In contrast, in the Maritimes the only known chemotype there is the 3-A DON chemotype.

One of the main implications affects the FDK and DON ratio that is used by our grain inspectors and elevator operators to visually estimate the DON content of grain.

Because the 3-A DON type has a potential for higher toxin production the tolerances for FDK, in August 2010, needed to be changed to meet customers' demand in ensuring grain quality.

Dr Graefenhan says the 3-A DON chemotype is a good example of why we need to monitor the occurrence and distribution of newly introduced plant pathogens and suggests we need to be watching for fusarium species that have not yet been detected in Canada but are well known on other continents as well as for the new Fusarium graminearum chemotype.