Ministry of Agriculture and Lands
Apple Fungicides - Resistance Management
Updated November, 2009
The following table lists fungicides registered for use on apple in British Columbia for apple scab and powdery mildew, categorized by resistance group.
Products in the same group have similar or identical modes of action. Over-use of products in one class of compounds will lead to resistance problems. See recommendations below for resistance management.
| Fungicide | Group* | Class | Diseases | Risk of Resistance |
| Nova (myclobutanil) | 3 | DMI Fungicides - Triazoles | Apple Scab, Powdery Mildew | Medium. Resistance may be developing (powdery mildews) |
| Nustar (flusilazole) | 3 | DMI Fungicides - Triazoles | Apple Scab, Powdery Mildew | |
| Pristine (boscalid + pyraclostrobin) | 7 + 11 | Pyridine carboxamides + QoI Fungicides | Apple Scab, Powdery Mildew | Boscalid - medium; |
| Sovran (kresoxim-methyl) | 11 | QoI Fungicides | Apple Scab, Powdery Mildew | High |
| Flint (trifloxystrobin) | 11 | QoI Fungicides | Apple Scab, Powdery Mildew | |
| Vangard (cyprodinil) | 9 | Anilinopyrimidines | Apple Scab | Medium |
| Scala (pyrimethanil) | 9 | Anilinopyrimidines | Apple Scab | |
| Captan/Maestro | M4 | Phthalimides | Apple Scab | Low |
| Dithane/Manzate (mancozeb) | M3 | Dithiocarbamates | Apple Scab | Low |
| Polyram (metiram) | M3 | Dithiocarbamates | Apple Scab | Low |
| Ziram | M3 | Dithiocarbamates | Apple Scab (pinpoint) | Low |
| Kumulus (sulphur) | M1 | Inorganics | Powdery Mildew, some activity on scab | Low |
| Serenade Max | NC | Biologicals | Powdery Mildew, Fire Blight (suppression) | Low |
| Senator (thiophanate-methyl) | 1 | Benzimidazoles | Apple Scab, Powdery Mildew | High. Apple scab resistance present. Not recommended for use on apple in B.C.. |
*M = multi-site inhibitor; NC = not classified
Fungicide Resistance Management
Fungicide resistance management is important to prolong the effectiveness of "at risk" fungicides and to limit crop losses should resistance occur.
To help prevent resistance from developing:
- Alternate between different fungicide groups. Do not use more than 2 back-to-back sprays of fungicides with the same group number. In particular, use products rated with a medium to high risk carefully, and limit the number of applications. Products with a low risk of resistance can generally be used more often.
- Use recommended tank mixes.
- Use only recommended dose rates.
- Ensure sprayer is properly calibrated to deliver accurate and thorough coverage.
- Limit use of eradicants to the early “primary scab” season. Switch to other protectant fungicides after mid-June.
- Integrate with non-chemical control methods.
- Discontinue use of a product if resistance is suspected and consult your crop advisor.
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