| Common name (example trade name) |
Chemical class | Activity | Mode of action (FRAC group number1) |
Resistance potential | Comments | |
|---|---|---|---|---|---|---|
| azoxystrobin (Quadris, Abound discontinued) | QoI5 | contact, systemic2 | single-site (11) | high3 | ||
| Bacillus pumilis (Sonata) | biological-bacteria | contact | BM 02 | low | ||
| Bacillus subtilis (Serenade) | biological-bacteria | contact | BM 02 | low | ||
| boscalid/pyraclostrobin (Pristine) | SDHI6 and QoI5 | contact, systemic2 | single-site/ single-site (7/11) |
medium | ||
| captan | phthalimide | contact | multi-site (M 04) | low | highly toxic to honey bee larvae | |
| copper | inorganic | contact | multi-site (M 01) | low | ||
| copper hydroxide | inorganic | contact | multi-site (M 01) | low | ||
| copper sulfate | inorganic | contact | multi-site (M 01) | low | ||
| cyflufenamid (Torino) | phenyl-acetamide | contact | unknown (U 06) | high | ||
| cyprodinil (Vangard) | anilinopyrimidine | contact, systemic on some crops | single-site (9) | high3 | ||
| cyprodinil/fludioxonil (Switch) | anilinopyrimidine and phenylpyrrole | contact, slightly systemic | single-site/ single-site (9/12) | low | ||
| difenoconazole/azoxystrobin (Quadris Top) | DMI4-triazole and QoI5 | contact and systemic (local)2 | single-site/ single-site (3/11) | high | ||
| difenoconazole/cyprodinil (Inspire Super) | DMI4 and anilinopyrimidine | contact, systemic2 | single-site/ single-site (3/9) | medium | ||
| fenhexamid (Elevate) | hydroxyanilide | contact | single-site (17) | high3 | ||
| fluopyram/tebuconazole (Luna Experience) | SDHI6 pyridinyl-ethyl-benzamide and DMI4 | contact, systemic2 | single-site/ single-site (7/3) | medium | ||
| iprodione (Rovral) | dicarboximide | systemic (local) | single-site? (2) | low | ||
| kresoxim-methyl (Sovran) | QoI5 | contact, systemic2 | single-site (11) | high3 | ||
| mancozeb (Dithane) | dithiocarbamate | contact | multi-site (M 03) | low | ||
| mefenoxam (Ridomil Gold) | phenylamide | contact, systemic | single-site (4) | high3 | ||
| metrafenone (Vivando) | benzophenone | contact | singe-site (50) | high | ||
| mineral oil (JMS stylet oil) | mineral oil | contact | various (NC) | low | ||
| myclobutanil (Rally) | DMI4-triazole | systemic (local)2 | single-site (3) | high | ||
| potassium bicarbonate (Armicarb, Kaligreen, Milstop) | inorganic salt | contact | various (NC) | low | ||
| potassium salts of fatty acids (M-Pede) | inorganic salt | contact | (NC) | low | ||
| pyrimethanil (Scala) | anilinopyrimidine | contact, systemic on some crops | single-site (9) | high3 | ||
| quinoxyfen (Quintec) | quinoline | contact | single-site (13) | high | ||
| sulfur | inorganic | contact | multi-site (M 02) | low | highly toxic to native strains of western predatory mite (Galen-dromus occidentalis) and parasites. | |
| tebuconazole (Elite**) | DMI4-triazole | systemic (local)2 | single-site (3) | high | ||
| tetraconazole (Mettle) | DMI4-triazole | systemic (local)2 | single-site (3) | high | ||
| thiophanate-methyl (Topsin) | MBC7 | systemic (local) | single-site (1) | high3 | ||
| trifloxystrobin (Flint Extra) | QoI5 | contact, systemic2 | single site (11) | high3 | ||
| triflumizole (Procure) | DMI4-imidazole | systemic (local)2 | single-site (3) | high | ||
| ziram | dithiocarbamate | contact | multi-site (M 03) | low | ||
| ** | Not registered, label withdrawn or inactive in California (maybe registered federally). |
| 1 | Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of action (for more information, see www.frac.info). 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 | Unsure or lacking scientific evidence. For fungicides, a question mark indicates general acceptance of systemic action based on performance data, but may not have been proven experimentally using lab assays (e.g., radioactively labeled compounds). |
| 3 | 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. |
| 4 | DMI = demethylation (sterol) inhibitor |
| 5 | Qol = quinone outside inhibitor (strobilurin) |
| 6 | SDHI = succinate dehydrogenase inhibitor |
| 7 | MBC = methyl benzimidazole carbamate |
| NC | not classified |
Acknowledgment: Adaskaveg et al., 2025. Fungicides, Bactericides, Biocontrols, and Natural Products for Deciduous Tree Fruit and Nut, Citrus, Strawberry, and Vine Crops in California. (PDF)