| 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)