Potato – Late Blight (Irish Blight)

Crop(s):          Potato

Disease(s):     Late blight (Irish blight)

Resistance Management Strategy for:

Group 4               Phenylamides (PA);
Group 11             Quinone outside inhibitors (QoI);
Group 21             Quinone inside inhibitors (QiI);
Group 28 + 43    Carbamates + benzamides; and

Group 40             Carboxylic acid amides (CAA).

  1. Start disease control early and maintain a regular program using a fungicide from groups other than Group 4, 11 or 40.
  2. When conditions favour disease development, do not wait for disease to appear, but apply two consecutive sprays of a Group 4, 11, 40 or 28 + 43 fungicide at the interval recommended on the label. Then resume the program of sprays using products from a different group to the Group 4, 11, 40 or 28 + 43 fungicides just applied.
  3. Do not apply more than four sprays of a Group 4 or 40 fungicide per season.
  4. Do not apply more than two sprays of a Group 28 + 43 product per crop.
  5. Apply Group 11 fungicides preventively. The total number of Group 11 fungicide applications per season should not exceed one third of the total number of fungicide applications per crop. No more than two consecutive Group 11 sprays should be applied.  If consecutive applications of Group 11 fungicides are used, then they must be followed by at least the same number of applications of fungicide(s) from a different group(s) before a Group 11 fungicide is used again, either in the current or following season.
  6. Apply Group 21 fungicides preventatively. The total number of Group 21 fungicide applications should not exceed six.


URL: https://croplife.org.au/resources/programs/resistance-management/potato-late-blight-irish-blight/
Content last updated: July 14, 2023

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 www.apvma.gov.au

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 14 July 2023. All previous versions of this strategy are now invalid.