Fusarium head blight (Fusarium graminearum)

Fusarium head blight: biology

Fusarium head blight (FHB) is a fungal disease of cereal crops caused primarily by Fusarium graminearum. The disease pathogen overwinters on crop residue or within infected seed. Warm, humid weather at flowering and head filling favours infection as spores germinate in warm moist weather of 16-30°C. Fusarium graminearum produces two different spore types: one spread by wind and the other spread by water splash from rain or irrigation. Spores also have the ability to overwinter in infected seed or infect plants directly as seedlings emerge. The disease can savage a cereal crop and is responsible for up to $1.5 billion in lost income to growers every year¹.

In Western Canada, FHB is most severe in the Red River Valley, south central Manitoba, and eastern Saskatchewan. In Alberta, Fusarium graminearum is being isolated with increasing frequency, especially in southern Alberta².

In Ontario, Fusarium head blight is the most important and yield-limiting disease of winter wheat.

In wheat, symptoms include premature bleaching of a few, or sometimes all, florets. Infections result in sterility and small white-to-pink shriveled seed.

In barley, symptoms can include brownish, darker spots on the barley heads. Sometimes pink or orangish spores may appear on the glumes or hulls.

FHB results in a reduction in yield due to sterility and smaller grains. Downgrading due to discoloured and shriveled seed also impacts the final grain price with farmers losing as much as $100 per acre from the downgrading of grain.³ Additionally, FHB infected grain may contain mycotoxins. Deoxynivalenol (DON) is one of these and is extremely toxic to a number of livestock as well as humans, making it unsuitable for feed, food or malt.