Agronomy •  2022-06-10

Saving Canada’s Strawberry Crops from Powdery Mildew

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Powdery mildew is a major fungal disease that impacts all parts of the strawberry plant, including leaves, stolons, flowers and berries.1

While it’s tricky to identify and is commonly mistaken with other diseases, Canada’s strawberry growers must be on high alert as powdery mildew is very difficult to manage once established within a field. The disease can also spread quickly, causing up to 30 per cent yield losses.2

Identifying powdery mildew in strawberries

With powdery mildew, delicate white fungal growth will appear on infected strawberries, and leaf edges will curl up and inwards.3Often, the disease can be first spotted on older leaves.

There is no threshold for powdery mildew in strawberries, so management should be based on field history, environmental conditions, and disease presence and severity.4

Risk factors

  • High humidity and warm conditions. Does not need leaf moisture.
  • Time of year. Higher risk in early warm springs and mid-late summer.
  • History of infection. In fields with a history of infection, begin sprays before any symptoms are found5.

How to manage powdery mildew

  • Manage weeds within the field to help increase air flow and reduce humidity.
  • Renovate June-bearing plantings as soon as harvest is complete to destroy infected tissue, as the disease will overwinter on old plant tissue and persist into the next season.
  • Fungicide applications should be applied at first sign of symptoms when conditions are conducive to disease development.
  • Once the disease is found in the field, multiple fungicide applications may be needed to keep infection levels down.

Nova™ Fungicide

Nova™ fungicide is a systemic, Group 3 fungicide for the control of various diseases affecting strawberries, apples, grapes and other crops. An advanced solution that meets strawberry farmers’ needs, it provides long-lasting and effective control of powdery mildew, with a maximum of six applications per growing season.

To improve the crop quality of your strawberries, contact our horticulture experts about controlling powdery mildew with Nova Fungicide.


1Carisse, O.; Maas, J. Les maladies du fraisier. In Our Strawberries/Les Fraises de Chez Nous; Khanizadeh, S., DeEll, J., Eds.; Gouvernement du Canada, Les éditions et Services de dépôt: Ottawa, ON, Canada, 2005; p. 551. ISBN 0660623382.
2Carisse, O.; Morissette-Thomas, V.; Van der Heyden, H. Lagged association between powdery mildew leaf severity, airborne inoculum, weather, and crop losses in strawberry. Phytopathology 2013, 103, 811–821. [CrossRef] [PubMed]