Should I Spray?

To get the highest levels of disease control, a fungicide should be applied before the disease shows itself.

Just because you can’t see it, doesn’t mean it isn’t there

Source: 2011 Canadian Plant Disease Survey, The Canadian Phytopathological Society, May 2011.

Things to consider as you head into the growing season:

• Rotation is one factor that will help determine your risk of infection, as sclerotinia only affects and can be hosted on broadleaf crops and weeds.
• Because sclerotinia can overwinter in the soil for up to five years it can rotate back into your crop. Additionally, sclerotinia spores are known to travel up to 1 km in distance.
• To get the highest levels of disease suppression, a fungicide should be applied before the disease shows itself – the ideal time to spray is before you know disease is a problem.
• If you choose to wait for more evidence of the disease, assess your crop at the beginning of flowering, or when 75% of the canola plants have at least three open flowers. At this point, apothecia, tiny golf tee shaped structures, can be seen in the soil. Then look at the previous 30-day moisture levels and forecasted temperature to help determine disease potential.
• Other factors that should be considered include disease pressure from the previous year and seed variety chosen as both can indicate the risk for an outbreak.

There are other tools and resources available to help assess the sclerotinia risk potential in your canola crop:

• Petal test kits and in-field diagnostic kits are available from your local retailer or agronomist.
• A checklist or Risk Assessment Tool, which helps you assess the sclerotinia risk potential in your area.
• Or use the Sclerotinia Spraying Decision Guide to help make your decision easier.

Once your level of risk has been identified, the ROI Calculator will help you calculate your possible return on investment based on your decision to spray.