| Common name (example trade name) |
Chemical class | Activity | Mode of action (group number)1 |
Resistance potential | Comments |
|---|---|---|---|---|---|
| azoxystrobin (Abound) | Qol2 | contact, systemic7 | single-site (11) | high8 | |
| bordeaux | inorganic | contact | multi-site (M1) | low | |
| captan | phthalimide | contact | multi-site (M4) | low | highly toxic to honey bee larvae |
| chlorothalonil (Bravo, Echo) | chloronitrile | contact | multi-site (M5) | low | |
| copper | inorganic | contact | multi-site (M1) | low | |
| cyprodinil (Vangard) | anilinopyrimidine | mostly contact, slightly systemic (on most crops) | single-site (9) | high8 | |
| dicloran (Botran) | aromatic hydrocarbon | contact, systemic | single-site (14) | medium | |
| fenbuconazole (Indar) | DMI3-triazole | systemic (local) 7 | single-site (3) | high | |
| fenhexamid (Elevate) | hydroxyanilide | contact | single-site (17) | high8 | |
| fosetyl-al (Aliette) | ethyl phosphonates | systemic | unknown (33) | low | |
| iprodione (Rovral) | dicarboximide | systemic (local) | single-site?(2) | low to medium | toxic to honey bee larvae |
| mefenoxam (Ridomil Gold) | phenylamide | contact, systemic | single-site (4) | high8 | |
| metconazole (Quash) | DMI3-triazole | systemic (local) 7 | single-site (3) | high | |
| myclobutanil (Rally) | DMI3-triazole | systemic (local) 7 | single-site (3) | high | |
| propiconazole (Bumper/Tilt) | DMI3-triazole | systemic (local) 7 | single-site (3) | high | |
| pyraclostrobin/boscalid (Pristine) | Qol2/SDHI5 | contact, systemic7 | single-site/single-site (11/7) | medium to high | |
| pyrimethanil (Scala) | anilinopyrimidine | mostly contact, slightly systemic (on most crops) | single-site (9) | high8 | |
| quinoxyfen (Quintec) | quinoline | contact | single-site (13) | medium to high | |
| sulfur | inorganic | contact | multi-site (M2) | low | highly toxic to native strains of western predatory mite (Galendromus occidentalis) and to parasites |
| tebuconazole (Elite) | DMI3-triazole | systemic (local) 7 | single-site (3) | high | |
| tebuconazole/trifloxystrobin (Adament) | DMI3-triazole/Qol2 | contact and systemic (local)7 | single-site/ single-site (3/11) |
medium to high | |
| thiophanate-methyl (Topsin) | MBC6 | systemic (local) | single-site (1) | high to very high8 | |
| trifloxystrobin (Gem) | Qol2 | contact, systemic7 | single-site (11) | high8 | |
| ziram | carbamate (DMDC4) | 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 Qol = quinone outside inhibitor (strobilurin) |
| 3 DMI = demethylation (sterol) inhibitor |
| 4 DMDC = dimethyl dithiocarbamate |
| 5 SDHI = Succinate dehydrogenase inhibitor |
| 6 MBC = Methyl benzimidazole carbamate |
| 7 Fungicide is generally considered to have systemic action based on performance data, but this characteristic has not been necessarily proven experimentally using more rigorous assays (e.g., radioactively labeled compounds). |
| 8 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)