• Pest & Disease

Monitoring and Managing White Mold in Canola

Monitoring and Managing White Mold in Canola
Kyle Okke
Dickinson, ND
It would be nice if we could just sit back and enjoy the view when canola reaches its most photogenic stage, but unfortunately white mold can seriously impact your crop before it blooms when the conditions are right. Therefore, it’s important to monitor the conditions and prepare to manage against the disease if it appears.
Observe moisture and temperatures
There are several environmental conditions that need to exist for white mold (sclerotinia) to develop. Soil moisture before bloom is crucial because it’s the trigger for spore release. There’s a good chance for mold issues if 1-2 inches of rainfall occur in a 1-2 week period when canola plants start to bolt. A dense canopy will also retain moisture after those rains and provide the right environment for white mold development.
If moderate temperatures in the 70s and wetness like rain, fog or heavy dews occur during bloom periods, the chances of infestation increase. Although warmer temperatures decrease the chance of infestation, warm/hot conditions don’t always mean that white mold will dry up and no longer present an issue. The climate from the ground up to the flowers is the concern – not the air temperature elsewhere.
I recommend using the Sclerotinia Risk in Canola Forecast Program website to track the progression of the disease during the growing season. A service of the Northern Canola Growers Association and North Dakota State University (NDSU), it monitors canola bloom stage and soil moisture levels.
Three fungicide application considerations
Overall, we’re fortunate that fungicides can help manage white mold better in canola than other susceptible crops. The right timing, bloom stage and application techniques can help you reduce the impact the disease can have on your crop:
1. Timing is very important: Most fungicides are labeled from 20 to 50 percent bloom, with the most common recommendations in the 20 to 30 percent bloom period. These early applications are made so that the fungicide is put on to protect the flowers from becoming an infection point. Infected petals can fall onto leaves and leaf bases attached to the main stem, causing more white mold infection – the kind that reduces yield potential by killing the plant from that point up. Early infections are typically the worst, as they have the most time to grow and spread as the season progresses.
2. Bloom stage: Pay close attention to bloom stage, as it can progress relatively slow or fast depending on soil moisture and more importantly, air temperature. A canola field can change by 10 percent per day if conditions are right. Make the decision to spray before fields start to bloom, to avoid delays during this important stage.
3. Application techniques: Most fungicides that protect against white mold are locally systemic, which means coverage will be important. The objective is to deliver active ingredient to as many flowers as possible and make sure the petals retain the droplets, as the petals are what carry in pathogen to the lower canopy to infect stems. This makes proper droplet size essential. Here are some things to consider:
  • Use a nozzle that delivers a fine-medium spray droplet. A standard flat fan XR nozzle is a good option. Maintain operating pressures of 30-40 PSI with these spray tips. Nozzles that deliver coarse or very coarse droplets (air Induction or other venture tips) should not be used, since fungicide will reach less surface area and larger droplets may simply bounce off of intended targets.
  • Water use rates of 10-15 gallons are best.
  • Include MasterLock® adjuvant in your tank mix to spread droplets out over surfaces and reduce loss from bounce and evaporation. Improving coverage and retention will result in more active ingredient reaching the plant.
As far as fungicides are concerned, products like Proline®, Topsin®, Quash® and Endura® fungicides all work well. Don’t get hung up on which product is the “best one.” Instead focus on the three management points mentioned to make your selection as effective as it can be.
Contact your locally owned and operated WinField® United retailer with questions about defending against white mold in your fields. They can help you put together a customized management plan for your acres.
© 2020 WinField United. Important: Before use always read and follow label instructions. Crop performance is dependent on several factors many of which are beyond the control of WinField United, including without limitation, soil type, pest pressures, agronomic practices, and weather conditions. Growers are encouraged to consider data from multiple locations, over multiple years, and be mindful of how such agronomic conditions could impact results. CROPLAN®, MasterLock® and WinField® are trademarks of WinField United. Proline® is a registered trademark of Bayer. Quash® is a registered trademark of Valent U.S.A. Corporation. Topsin® is a registered trademark of Nippon Soda Company, Ltd. Endura® is a registered trademark of BASF.

Thank You for Signing Up.

Get the latest insights and tips – directly to your inbox

Subscribe to our Advisor e-newsletter, keeping you up to date on the latest news, information and agronomic tips in the industry, national and local.

By signing up for WinField United emails, you agree to receive promotional information from WinField United. The emails will contain valuable agronomic insights, the latest WinField United product information and field updates. For more information about our privacy policy, please review it here.


Yes, sign me up for my local . ​

Enter your contact details and we’ll start delivering your local report to your inbox, based on the zip code you provide.



Thank you for your request. One of our expert agronomists will be reaching out to you shortly.