Detect and prevent smut in cereals

Covered and loose smuts reduce yield and quality

This year, agronomists in Saskatchewan saw a higher-than-normal rate of smut disease in barley and wheat fields where the seed was not treated before planting. We also saw smut in some fields where seed was treated but did not receive adequate coverage.

Smut can be a significant threat to production, as yield losses are directly related to the percentage of diseased tillers. If 10% of the plants in a field have smut, you will see a 10% yield loss. Some types of smut also affect grain quality, and maltsters generally have zero tolerance for smutted barley. 

Smut spores are fine and lightweight, and as such, even a gentle breeze can spread spores across a field and into neighbouring ones. If there’s smut in the area of your wheat or barley fields, get the seed tested before replanting. 

There are two types of smuts on the Prairies:

Covered smut (also called common bunt)

• Transmission: Externally seed-borne – spores from diseased plant heads attach to the surface of healthy seeds.
• Result: Causes a reduction in crop yield and quality.
• Preferred Conditions: Thrives when seeding into cold soil in late fall and early spring.

Detection: Scout during grain filling; in plants infected with smut, a blackened mass of spores replaces individual kernels in the head.
(Source: Alberta Barley)

True loose smut (commonly called loose smut)

• Transmission: Internally seed-borne – spreads when infected seed is planted.
• Result: Does not affect marketability or quality of grain sold to the elevator because all parts of the infected head, except the rachis (central stalk), are replaced with a mass of brown spores; the spores do not affect the marketability or quality of the grain, they only affect the yield.
• Preferred Conditions: Thrives in cool, wet, July weather.
• Detection: Can be detected through seed testing and scouting—the most common timing is at head emergence; symptoms can be seen later in the season as bare rachis. (Source: University of Saskatchewan)

Here are some potential causes behind the increased presence of smuts and what you can do to prevent it.

Cause: The seeds planted this year were contaminated

Prevention: Get your cereal seed tested at a lab before deciding to plant it. If there’s less than 1% smut in the sample, seed treatment is generally unnecessary. If there’s 1-5% smut in the seed, get it treated. If there’s more than 5% smut, get new seed.

As a rule, I recommend treating all barley seed, even if there’s less than 1% smut in the sample. Barley has low resistance to this disease.

Cause: Choice of seed treatment used or poor seed coverage

Prevention: The only way to prevent smut in Canada is through seed treatment. In Australia, some studies have shown that foliar fungicide applied at heading timing can reduce smut infection the following season. However, that research is still in its early days, and there are no foliar products registered for smut in our growing regions.

Treatments

Not all seed treatments provide the same level of smut control. Check your seed treatment product label to see what it offers. I have had great results using Raxil® PRO. Other commonly used seed treatments that are labelled for smut include Insure® Cereal FX4, Vibrance® Quattro, Cruiser® Vibrance® Quattro and RANCONA® TRIO.

Even with the best systemic fungicide, you’ll lose control if coverage is poor. Using a service like Cargill’s Storm Pro Mobile Seed Treater  takes the guesswork out of seed treatment. A properly calibrated auger and applicator ensure that you’re not over- or under-treating your seed. It does take some forward planning, so if you’ve had issues with seed treatment performance in the past, call your agronomist when you book your seed. We can bring the seed treater to you to ensure your seed is ready to go when you are.

^{Always read and follow label directions.}

^{INSURE is a trademark of BASF SE. Raxil is a trademark of the Bayer Group. RANCONA is a trademark of Arysta LifeScience Canada Inc. CRUISER and VIBRANCE are trademarks of a Syngenta Group Company.}