Agronomy •  2022-04-05

Protecting your canola from Sclerotinia takes a proactive one-two punch

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sclerontinia root rot

Sclerotinia stem rot is one of the most predominant canola diseases in Western Canada, observed in 80 per cent of surveyed crops in a 2020 study.1 While damage can vary year to year, up to 50 per cent yield loss can be seen in canola fields with high inoculum loads and environmental conditions favorable to the disease.

With up to half your canola yield at risk, farmers must take a proactive multi-pronged approach against Sclerotinia. While foliar fungicides can help, they should be combined with other control methods - because once you see disease symptoms in your crop, it is too late to spray.

Sclerotinia in canola  

Infection occurs during flowering from airborne spores and is highly dependent on weather conditions at the time of infection.

Wet conditions, moist soil, high humidity and temperatures between 15-25°C within the crop canopy are conducive to sclerotia germination. Once infected, the disease can cause lesions, bleached and weak stems, premature ripening, crop lodging and reduced yields from fewer pods and seeds.

Yield loss calculator

Yield loss calculation

  • Yield losses are estimated to be half the level of infection.
  • To calculate revenue loss/acre, multiply percent potential yield loss by estimated yield by cost per bushel.

Tips for proactive Sclerotinia management

To protect your canola yield, here are some proactive steps you can take to manage your crop’s risk from Sclerotinia: 

Grow Sclerotinia resistant canola hybrids

Practice crop rotation

  • Valuable when crops in rotation are not susceptible to Sclerotinia, such as cereals or corn
  • Rotation to non-host crops is important, but keep in mind that sclerotia bodies from Sclerotinia can survive in the soil for up to 7 years

Use a foliar fungicide

  • Consider making a fungicide application if you experience any of the following conditions:  
    • Warm soil temperatures through June and early July
    •  Soil moisture at or near field capacity through June and right up to flowering
    •  Presence of Sclerotinia in previous years
    •  Humidity levels in canopy and moisture on plants, allowing for ‘Petal stick‘
    • Frequent showers & moderate temperatures in July
    • Rainfall (at least 5-10 mm) on > than 2 days per week
    • Crop canopy wet throughout most of day
    • Temperatures day and night are warm vs. cool

Risk assessment and scouting

When deciding to use a fungicide, consider the economics

Take a canola field with an estimated yield of 40 bushels per acre that is expected to sell for $20 per bushel. If the yield loss due to Sclerotinia infection is only 15%, the revenue loss would be $120 per acre. If the cost of fungicide application was $30 per acre, then spraying a fungicide for Sclerotinia control would be very economical, in this example.


Growing Sclerotinia resistant canola hybrids

The first step to protecting your canola yield is growing a Sclerotinia resistant hybrid. Providing season-long control, canola hybrids with the Sclerotinia trait can reduce disease development by over 65 per cent, as well as lessen disease transfer through a reduction in disease transfer to the stem and reduction of disease severity in infected stems.

Corteva Agriscience was the first agriculture company to introduce Sclerotinia resistant canola hybrids in 2008. In development for over 20 years, the industry-leading canola protection trait is built right into high yielding canola hybrids such as Pioneer Protector® brand 45CS40 and P505MSL and new Brevant™ seeds B3014, providing farmers with peace of mind and protection when environmental conditions are conducive to Sclerotinia infection within their canola fields. 

Today, Corteva is hard at work developing the next generation of Sclerotinia resistant hybrids with the intent of reducing the incidence of the disease up to 80 per cent.

fieldSusceptible Canola Hybrid (left), Sclerotinia Resistant Canola Hybrid (right)

Maximize protection and reduce yield loss under severe disease pressure

Under high Sclerotinia pressure environments or areas prone to the disease, it’s best practice to make a proactive foliar fungicide application to protect your investment when choosing a Sclerotinia resistant hybrid and maximize your yield.

Acapela™ is a one-of-a-kind fungicide that quickly and efficiently surrounds, penetrates and protects the leaf and stem. Rapid absorption moves the fungicide quickly and efficiently into and within each plant, allowing application to occur even when field conditions are challenging, so farmers get healthier crops and higher yield potential. To maximize control, ideal timing is approximately 20-30 per cent bloom or before very few petals have fallen off the plants.

By choosing a hybrid with the Sclerotinia resistance trait and proactively applying a foliar fungicide like Acapela, you can maximize protection and reduce yield loss under severe disease pressure.

For more information on finding the right canola products with Sclerotinia resistance for you, contact your local Pioneer Sales Representative or Corteva retailer.