Saskatchewan, Canada
June 1, 2016
by Mitchell Japp, MSc, PAg, Provincial Specialist, Cereal Crops, Crops and Irrigation Branch
Fusarium head blight (FHB) is sneaky. By the time it visibly appears, it is too late to do anything about it. But it should not be ignored.
Producers with a good crop rotation and a variety with genetic resistance have a good start to managing FHB. Fungicides are used for in-crop FHB management.
FHB is a mono-cyclic disease. Once the crop is infected, it is infected. No management prevents further infection. Symptoms do not appear until after infection. So, how should a producer decide to spray, and when?
FHB risk maps will once again be available on the Sask Wheat website starting in mid-June. The maps are based on a risk model that assesses the conditions that favour fusarium to determine the likelihood that infection may occur. Fusarium is favoured by warm, moist conditions; rain splash and wind can help move the spores into the upper canopy.
Weather is one factor, but crop staging is also important. Producers must know their heading date to use the risk maps. Wheat is most susceptible to fusarium when the florets are open, but infection can occur until the soft dough stage. The risk maps are updated daily, so producers need to follow the maps that correspond to their heading date.
The risk maps are not the only tool to assess risk. Producers should consider the history of fusarium in the area, the susceptible period of the crop, and the cost of fungicide versus savings. The Saskatchewan Ministry of Agriculture developed a risk assessment tool to help producers decide whether or not to spray for FHB.
Fungicide can be used for FHB suppression when 75 per cent of the heads on the main stems are fully emerged to when 50 per cent of the heads on the main stems are in flower. Ideal timing is when there are yellow anthers in the middle of the head.
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