Agriculture: Apple Pest Management Guidelines

General Properties of Fungicides Used in Apples

Common name
(trade name)
Chemical class Activity Mode of action
(FRAC number)1
Resistance potential Comments
Bordeaux inorganic contact multi-site (M1) low
captan phthalimide contact multi-site (M4) low highly toxic to honey bee larvae
copper                                           inorganic contact multi-site (M1) low
cyprodinil (Vangard) anilinopyrimidine mostly contact, slightly systemic (on most crops) mostly contact single-site (9) high6
fenarimol (Rubigan) DMI2- pyrimidine systemic (local) single-site (3) high
kresoxim-methyl (Sovran) strobilurin contact and systemic (local) single-site (11) high6
mancozeb (Dithane) carbamate EBDC3 contact multi-site (M3) low
mefenoxam (Ridomil Gold) phenylamide contact and systemic single-site (4) high6
myclobutanil (Rally) DMI2-triazole systemic (local) single-site (3) high
pyrimethanil (Scala) anilinopyrimidine mostly contact, slightly systemic (on most crops) mostly contact single-site (9) high6
sulfur inorganic contact multi-site (M2) low highly toxic to native strains of western predatory mite (Galendromus occidentalis) and to parasites
thiophanate-methyl (Topsin-M) MBC5 systemic (local) single-site (1) very high6
trifloxystrobin (Flint) strobilurin contact and systemic single-site (11) high6
triflumizole (Procure) DMI2-imidazole systemic (local) single-site (3) high
ziram carbamate (DMDC)4 contact multi-site (M3) low
1    Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of action. Fungicides with different group numbers are suitable to alternate in a resistance management program. In California, make no more than one application of a fungicide with a mode-of-action group number associated with high resistance risk before rotating to a fungicide with a different mode-of-action group number; for other fungicides, make no more than two consecutive applications before rotating to fungicide with a different mode-of-action group number.
2    DMI = demethylation (sterol) inhibitor
3    EBDC = ethylene bisdithiocarbamate
4    DMDC = dimethyl dithiocarbamate
5    MBC = methyl benzimidazole carbamate
6    Resistance has been found in California for certain fungicides with a single-site mode of action. To reduce the risk of resistance development, take the mode of action into account when choosing a fungicide. At the beginning of a treatment program, use a fungicide with a multi-site mode of action; for subsequent applications rotate or mix fungicides with different mode of action FRAC numbers. Use labeled rates (preferably the upper range) of the single-site fungicides, and limit the total number of applications per season.

Acknowledgment: Adaskaveg et al., 2022. Fungicides, Bactericides, Biocontrols, and Natural Products for Deciduous Tree Fruit and Nut, Citrus, Strawberry, and Vine Crops in California. (PDF)

Text Updated: 03/09