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Priwen Fungicide Bayer CropScience



Priwen fungicide provides a new fungicide Group for use in Canadian wine grapes to protect against powdery mildew. It’s a Group 5 foliar fungicide providing systemic protection and post-infection activity. And because it’s a unique Group for wine grapes, it’s an excellent resistance management tool for Canadian growers.

Product Summary


Product Type

  • Fungicide


  • Wine Grapes
Diseases Controlled

Diseases Controlled (Top 3)

  • Powdery Mildew
Diseases Supressed

Diseases Suppressed (Top 3)

Groups and Active Ingredients

Groups and Active Ingredients

  • Spiroxamine Group 5
Formulation Type

Formulation Type

  • Emulsifiable Concentrate


  • Available in 1 L jugs and 12 x 1L cases

Active Ingredients



Pests Controlled

Powdery mildew

Province of Registration

British Columbia
New Brunswick
Northwest Territories
Nova Scotia
Prince Edward Island

Application Tips

Wine Grapes
Disease Rate Application Timing Maximum Applications Rainfast Pre-Harvest Interval

Powdery mildew (Uncinula necator)

400-600 mL/ha
(162-243 mL/ac.)

Use the higher rate when conditions favour the development of heavy disease pressure or in vineyards with a history of heavy disease pressure

Apply Priwen anytime during the period from shoot emergence until 35 days before harvest

Allow 14 days between applications

Do not apply more than 1.2 L/hectare per season

When dry

35 days


  • 1 L jug, 12 X 1L case


Mixing Order

Add one-half of the required amount of water to the spray or mixing tank and start agitation.

Add the required quantity of Priwen fungicide to the water and complete filling with water to the required total volume. Maintain agitation throughout mixing and spraying.


Re-Entry Intervals
Re-Entry Activity Re-Entry Interval

Transplanting, scouting, hand pruning, hand weeding, propagating, bird control, trellis repairs

12 hours1

Irrigation (hand set)

3 days

Tying/training, hand harvesting, leaf pulling

17 days

Girdling, turning

24 days

1. A minimum of 12 hours is applicable for all agricultural workers to allow residues to dry and vapor to dissipate, hence limiting potential effects such as irritation or allergic reactions.


Crop Safety

Do not apply to table grapes due to the potential for adverse superficial effects.


Application Tips

Field Sprayer Application:

  • Do not apply during periods of dead calm, or when winds are gusty.
  • Do not apply when wind speed is greater than 16 km/h at the application site.
  • Do not apply with spray droplets smaller than the American Society of Agricultural Engineers (ASAE S572.1) medium classification
  • Boom height must be 60 cm or less above the crop or ground

Airblast Application:

  • Do not direct spray above plants to be treated
  • Turn off outward pointing nozzles at row ends and outer rows

Resistance Management

Avoid consecutive applications of Priwen fungicide in a season. Alternate applications with fungicides that have a different mode of action and that are also effective on powdery mildew.

Use tank mixes with fungicides from a different group that are effective on powdery mildew when such use is permitted.

Fungicide use should be based on an integrated pest management program that includes scouting, historical information related to pesticide use and crop rotation. Other considerations include host plant resistance, impact or environmental conditions on disease development, disease thresholds, as well as cultural, biological and other chemical control practices.