Apple Fungicides - Resistance Management

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
Nova (myclobutanil)	3	Triazole	Apple Scab, Powdery mildew
Nustar (flusilazole)	3	Triazole	Apple Scab, Powdery mildew
Sovran (kresoxim-methyl)	11	QoI (Strobilurin)	Apple Scab, Powdery mildew
Flint (trifloxystrobin)	11	QoI (Strobilurin)	Apple Scab, Powdery mildew
Vangard (cyprodinil)	9	Anilinopyrimidine	Apple Scab
Scala (pyrimethanil)	9	Anilinopyrimidine	Apple Scab
Captan/Maestro	M4	Phthalimide	Apple Scab
Dithane/Manzate (mancozeb)	M3	Dithiocarbamate	Apple Scab
Polyram (metiram)	M3	Dithiocarbamate	Apple Scab
Ziram	M3	Dithiocarbamate	Apple Scab (pinpoint)
Kumulus (sulphur)	M1	Inorganic	Powdery Mildew, some activity on scab
Senator (thiophanate-methyl)	1	Benzimidazole	Apple Scab, Powdery mildew; not recommended due to apple scab resistance.

*M = multi-site inhibitor

Fungicide Resistance Management

Fungicide resistance management is important to prolong the effectiveness of "at risk" fungicides and to limit crop losses should resistance occur. Nova and Nustar are at high risk of resistance due to over-use.  Sovran, Flint, Vangard and Scala are also at risk for resistance.  Senator is no longer recommended in the Okanagan for apple scab due to widespread resistance. 

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.
• 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.