Cucurbits – Powdery Mildew

Crop(s):          Cucurbits

Disease(s):     Powdery mildew

Resistance Management Strategy for:

Group 3               Demethylation inhibitors (DMI);
Group 7               Succinate dehydrogenase inhibitors (SDHI);
Group 8               Hydroxy-(2-amino-) pyrimidine;
Group 11             Quinone outside inhibitors (QoI);
Group 11 + 7      QoI + SDHI:
Group 13             Aza-napthalenes;
Group U6            Phenyl-acetamide; and
Group 50            Actin disruptors (aryl-phenyl-ketones).

  1. Start disease control early. Do not wait for powdery mildew to appear before spraying but start as soon as practicable after crop emergence.
  2. Use protectant sprays in early crop growth. Apply protectant sprays up to the fruit set stage of the crop if the disease normally occurs during this period.  If this schedule is interrupted (eg. by rain) use a tank mix of protectant plus systemic before recommencing the protectant program.
  3. After fruit set, use systemic fungicides in one or more of the following ways:
  4. Tank mix systemic fungicides with a protectant fungicide and use fungicides from at least two different systemic activity groups per crop.
  5. Alternate systemic fungicides with a protectant fungicide and use fungicides from at least two different systemic activity groups per crop.
  6. Alternate systemic fungicides from at least three different activity groups per crop.
  7. Apply Group 11 fungicides preventatively.
  8. Use a maximum of one Group 11 containing spray out of every three fungicide applications.
  9. Do not use consecutive applications of Group 11 or Group U6 fungicides.
  10. Do not apply more than two Group 11 (including Group 11+7) or Group U6 products per crop.
  11. Do not apply more than three Group 7 or Group 13 products per crop and no more than two consecutive applications per year.

Content last updated: July 16, 2021

CropLife Australia’s Resistance Management Strategies provide a guide for crop protection product rotation through product groups. The strategies are a useful tool that supports farmers’ adoption of resistance management. All crop protection products must be handled and applied strictly as specified on the product label or APVMA permits.

These Resistance Management Strategies do not replace product labels. They are a guide only and do not endorse particular products, groups of products or cultural methods in terms of their performance. It is important to check with the Australian regulator’s (APVMA) product database for contemporary information on products and active constituents. The database can be sourced through

The information given in this strategy is provided in good faith and without any liability for loss or damage suffered as a result of its application and use. Advice given in this strategy is valid as at 16 July 2021. All previous versions of this strategy are now invalid.