Introduction

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Integrated Plant Disease Management
Cereal Leaf Diseases
Plant Disease Control
Cereal leaf diseases affect both the yield and quality of cereals. The following management practices are recommended for
effective control of leaf diseases in all cereal crops.
• Scouting: Scout fields prior to, during, and following flag leaf emergence to check for disease levels. Flag and upper
leaves are responsible for 50 per cent or more of grain-fill.
• Crop Rotation: Rotate crop types [e.g. cereal (wheat)/oilseed/cereal(barley)/pulse] to reduce the build-up of disease
inoculum in crop residue. If at all possible, do not seed the same crop in back to back years. When a short rotation is
absolutely necessary, seed in the second year a variety that is more resistant to an anticipated disease problem.
• Resistant Varieties: Provincial crop/seed guides provide a comprehensive listing of the performance of adapted
varieties, including their resistance status to specific diseases.
• Foliar Fungicides: Foliar fungicides, applied at the proper time in accordance to manufacturers’ Pesticide Product
labels, can control cereal leaf diseases and help to attain target yields. The greatest benefit occurs when disease
pressure is high or with varieties that have poor resistance.
• Spraying Practices: Foliar fungicides should be applied preventively, before disease is well-established in a crop and
already causing crop loss. Good spray coverage with minimal drift is essential. Ideally, the best time to spray is when
the wind is light, humidity is above 60 per cent and air temperature is between 10 and 25 o C.
Ergot of Cereals
Ergot is a fungal disease that affects most cereals and grasses in Canada. Ergot bodies contain toxic alkaloids; they should
never be consumed by humans or fed to animals. Ergot is a particularly damaging disease of rye, and has also been
observed sporadically over the years on cereals and grasses in the prairie provinces. After an ergot outbreak, crop residue
and soil become contaminated with a higher load of ergot bodies, placing nearby grasses and cereal crops at greater risk
of infection in the following seasons. This risk increases further when cool, moist weather conditions promote ergot spore
production and/or when cereals experience an extended period of flowering or an induction of floret sterility due to any
of a variety of agronomic or environmental factors. Once ergot is present, little can be done to control the disease in the
field, so prevention is important. Planting seed contaminated with ergot bodies can potentially spread disease to previously
clean fields and there are no seed treatments registered; therefore only clean, healthy seed should be used. During the field
season, nearby grasses may be mowed to remove additional hosts. Prior to harvest, fields should be scouted to determine
where ergot has developed, such as headlands, and those areas should be harvested separately. Viability of ergot bodies
decreases after one to two years.
Disease Control
Fusarium Head Blight of Cereals
Fusarium head blight (FHB) causes a reduction in yield as a result of floret sterility and the loss of light weight cereal
kernels during combining. More important is the effect on grain quality and food safety due to production of myco- toxins,
including deoxynivalenol (DON) and vomitoxins. In Manitoba, FHB occurs throughout all crop regions and will damage
wheat crops whenever environmental conditions favour the disease. In Saskatchewan, FHB has been established in eastern
regions for several years, but occurs across the province, particularly in wet years.
• Field Management of FHB: Weather is by far the greatest factor in development of FHB. The disease is most likely to
develop when the plants are flowering, temperatures range from 15 to 30 o C and high moisture is continuous for 48 to
60 hours. If conditions remain warm and moist, the pathogen can continue to sporulate and spread to other kernels or
heads. Under these optimum conditions, crop management has little impact on FHB outbreaks. Production practices,
which lead to reduced tillering and shortened flowering duration, could reduce the risk period of FHB infection.
• Crop Rotation and Crop Selection: A break of at least one year – preferably two years – is advised between cereal,
grass and corn production. In fields of wheat on wheat stubble, the incidence of FHB was about one and a half times
higher than in fields of wheat planted into pulse crop residue. Regardless of the rotation, producers should consider
planting cereals that are less susceptible to FHB. Results from previous years show that durum and soft white wheat
varieties are more susceptible than hard red spring wheat varieties. Barley is more resistant than wheat, and oat is
more resistant than either wheat or barley. Refer to provincial seed guides for FHB disease ratings for each variety.