Fusarium Head Blight (FHB) is a fungal disease that can infect a number of crops in Canada – wheat, barley, oats, rye, corn, canary seed, and forage grasses. However, the crops most affected are wheat, barley, and corn. F. graminearum is only one of many species of Fusarium, but it is considered the most important one in Canada because of the impact it has on yield and grain quality, its ability to produce several different toxins, and its abundance in eastern Canada and the eastern prairies. In western Canada, F. graminearum is found most frequently in the black soil zone. This zone is also the area of highest rainfall on the prairies. Infection is associated with rainfall during the flowering stage. The infection is spread by wind, but the pathogen is also spread by planting infected seed.
Disease Cycle: Infection occurs when the ascospores land on susceptible wheat heads. If the florets are infected just after their emergence, the fungus will colonize and kill the florets and kernels will not develop. Florets that are infected later will produce diseased kernels that are shriveled and wilted, or “tombstone” in appearance. Kernels that are colonized by the pathogen during late kernel development may not appear to be affected, but may still be contaminated. Infected kernels may be used as seed for a subsequent wheat crop. These infected seeds, if left untreated, may give rise to blighted seedlings. The degree to which this occurs in the field depends on the percentage of infected seed and soil conditions affecting the growth and development of the seedlings.
Disease Control: Crop rotation and tillage have been shown to affect the incidence of FHB. In recent years, decreases in tillage are thought to have contributed to regional scab epidemics by increasing levels of inoculum available for infection. Chemical controls, such as fungicides, provide partial control of FHB. Biocontrol agents could play an important role in organic cereal production. In conventional production, such biocontrol agents may extend protection of spikes past the flowering stage after fungicides can no longer be applied.
In a normalized crop year the following information for the Fusarium graminearum percentage infection of seed should be used as a guide for your seeding considerations:
0-1% – the seed is safe to plant anywhere in Saskatchewan.
0-3% – the seed is safe to plant in the west side of Saskatchewan.
0-5% – the seed is safe to plant in the east side of Saskatchewan.
0% – the seed is safe to plant in Alberta.
*Please note that any presence of F. graminearum on seed should trigger the use of a registered seed treatment.
In a normalized crop year the following information for the total Fusarium percentage infection of seed should be used as a guide for your seeding considerations:
0-7% – the seed may not need to be treated with a registered seed treatment.
8-14% – the seed should be treated with a registered seed treatment.
> 14% – the seed should not be planted.