Twenty-six years of Fusarium head blight in western Canada

FHB status updateFusarium head blight incidence increased steadily after 1995, peaking in the epidemic year of 2016, but with low levels since then. Severity has remained relatively low over time, and not always correlated to incidence levels.

Fusarium head blight (FHB) emerged as a serious disease in western Canada in the early 1990s, and has a direct effect on wheat yield, germination, and end use quality. The production of harmful mycotoxins such as trichothecene deoxynivalenol (DON) is a food safety risk, and concentration levels are regulated in many countries.

Several different species of the genus Fusarium can cause FHB, with Fusarium graminearum being the most common species.

The objective of this study was to provide an update on the recent annual and regional trends of FHB incidence and severity in western Canada from 1995–2021 and DON from 2018–2021.

As part of the Canadian Grain Commission’s annual Harvest Sample programme (HSP), wheat samples of CWRW, CWRS, and CWAD wheat were received from across western Canada from 1995 to 2021. The total number of samples collected from the HSP was 208,247 during those years.

Samples were graded for Fusarium damaged kernels (FDK), and those with a level of 0.01% or greater were considered to have FDK presence. Subsequently, FHB incidence was calculated as a percentage of total samples containing FDK, and was broken out by wheat class, province, and crop district. FHB severity was determined as the percentage of FDK in a grain sample on a weight basis.

Standard laboratory analysis assessed DON levels for samples from 2018 to 2020.

A steady increase in FHB since 1995

Generally, FHB incidence was low in the mid-to late-1990s at less than 11%, but gradually increased, with incidence reaching 32% on CWRS, 33.7% on CWAD, and 46.2% on CWRW in the 2000s. Peak incidence was reached in the 2010s, reaching 68.2% for CWRW in 2014, and an epidemic year in 2016 for CWRS at 66.5% and CWAD at 79%, with severe financial losses in those years.

Since 2016, FHB incidence has declined, with an average during the drought year of 2021 of 0% in CWRW, 0.8% in CWRS, and 6% in CWAD.

FHB incidence and severity and DON for different wheat classes. FHB incidence and severity were recorded from 1995–2021, and DON was monitored in HSP from 2018–2021.

1995 – 2021 2018 – 2021
Wheat Class N samples Incidence (%) Severity (%) N samples Incidence (%) Severity (%) DON (mg/kg)
CWRW 4495 21.74 0.50 255 7.84 0.32 0.04
CWAD 47310 12.16 0.65 4914 9.14 0.50 0.13
CWRS 156442 16.40 0.43 21369 17.02 0.30 0.06

Source: T. Chin et al. 2023

Alberta had less FHB incidence in CWRW and CWRS than Saskatchewan and Manitoba when all years were combined. The eastern parts of Saskatchewan had higher incidence than the western part of the province. Manitoba had greater levels of FHB incidence in most years, particularly in the late 1990s and 2000s, the researchers reported.

Incidence of FHB in CWRW, CWAD, and CWRS wheat from 1995 to 2021

Source: T. Chen et al. 2023

Similar to FHB incidence, FHB severity was highest in Manitoba, followed by Saskatchewan and Alberta. Also, FHB severity was higher in CWAD compared to  CWRS, while severity in CWRW was more variable across the years.

In most years, wheat samples of all classes would not have been downgraded due to FDK in the samples. Even in the epidemic year of 2016, only 3.88% of CWRS samples would have been severely downgraded with a FDK severity of 4%. But CWAD was severely impacted in 2016 with 27.73% of CWAD samples downgraded with more than 4% FDK.

DON analysis was added to the Canadian Grain Commission’s HSP in 2018. For all wheat classes, most samples had DON levels below the limit of detection in every year. This was likely related to the low FDK incidence and severity since 2018. Only 0.72% of samples exceeded the Codex Alimentarius Commission maximum limit of 2 mg/kg level. These samples could likely have been cleaned prior to sale to reduce downgrading.

There was some variation between years and wheat classes, with CWAD having a higher average level of DON compared to CWRS, with CWRW having the lowest DON levels.

Similar to other research, there was a correlation between FHB severity and DON levels, and was consistent across the 3 wheat classes.

These results and on-going disease survey and monitoring can help researchers, plant breeders, and agronomists develop integrated FHB management strategies.

The researchers acknowledge the decades of work by all of those involved in the Harvest Sample Program, the Inspection Services division of the Grain Commission, Analytical Services unit within the Grain Research Laboratory, and the producers who participated in the programme.

Tiffany Chin, Kerri Pleskach, Sheryl A. Tittlemier, Maria Antonia Henriquez, Janice Bamforth, Niradha Withana Gamage, Tehreem Ashfaq, Sung-Jong Lee, Mayantha Shimosh Kurera, Bhaktiben Patel & Sean Walkowiak (2023): A status update on fusarium head blight on Western Canadian wheat, Canadian Journal of Plant Pathology


Photo courtesy Sean Walkowiak

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