| Common name (Example trade name) |
Chemical class (FRAC #)1 |
Activity | Mode of action | Resistance potential | Comments |
|---|---|---|---|---|---|
| azoxystrobin (Quadris, Abound discontinued) | Qol5 (11) | contact, systemic7 | single-site | high6 | |
| azoxystrobin/difenoconazole (Quadris Top) | QoI5/DMI2-triazole (11/3) | contact, systemic (local)7 | single-site/ single-site |
medium | |
| azoxystrobin/propiconazole (Quilt Xcel) | QoI5/DMI2-triazole (11/3) | contact, systemic (local)7 | single-site/ single-site |
medium | |
| captan (Captan) | phthalimide (M 04) | contact | multi-site | low | highly toxic to honey bee larvae |
| chlorothalonil (Bravo/etc.) | chloronitrile (M 05) | contact | multi-site | low | |
| dicloran (Botran 75W) | aromatic hydrocarbon (14) | contact/systemic7 | single–site | medium | |
| fenarimol (Rubigan**) | DMI2-pyrimidine (3) | systemic (local)7 | single-site | high | |
| fenbuconazole (Indar) | DMI2-triazole (3) | systemic (local)7 | single-site | high | |
| fenhexamid () | hydroxyanilide (17) | contact | single-site | high6 | pre- and postharvest |
| fludioxonil (Scholar) | phenylpyrrole (12) | systemic | single-site | medium | postharvest on fruit |
| fluopyram/trifloxystrobin (Luna Sensation) | SDHI4/QoI5 (7/11) | contact, systemic7 | single-site/ single-site |
medium | postharvest on fruit |
| fosetyl-al (Aliette) | ethyl phosphonate (P 07,33) | systemic | unknown | low | |
| iprodione (Rovral/Nevado) | dicarboximide (2) | systemic (local) | single-site? | low | |
| mefenoxam (Ridomil Gold) | phenylamide (4) | contact, systemic | single-site | high6 | |
| metconazole (Quash) | DMI2-triazole (3) | systemic (local) | single-site | high | |
| myclobutanil (Rally) | DMI2-triazole (3) | systemic (local) | single-site | high | |
| penthiopyrad (Fontelis) | SDHI4 (7) | contact | single-site | high6 | |
| propiconazole (Bumper**) | DMI2-triazole (3) | systemic (local)7 | single-site | high | pre- and postharvest |
| pyraclostrobin/boscalid (Pristine) | QoI5/SDHI4 (11/7) | contact, systemic7 | single-site/ single-site | medium | |
| quinoxyfen (Quintec) | quinoline (13) | contact | single-site | high | |
| sulfur | inorganic (M 02) | contact | multi-site | low | highly toxic to native strains of western predatory mite (Galendromus occidentalis) and to parasites |
| tebuconazole (Elite**) | DMI2-triazole (3) | systemic (local)7 | single-site | high | pre- and postharvest |
| tebuconazole/trifloxystrobin (Adament) | DMI2-triazole/QoI5 (3/11) | contact,systemic (local)7 | single-site/ single-site |
high | |
| thiophanate-methyl (Topsin-M) | MBC3 (1) | systemic (local) | single-site | high6 | |
| triflumizole (Procure) | DMI2-imidazole (3) | systemic (local)7 | single-site | high |
| 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. |
| 2 | DMI = demethylation (sterol) inhibitor |
| 3 | MBC = methyl benzimidazole carbamate |
| 4 | SDHI = succinate dehydrogenase inhibitor |
| 5 | QoI = quinone outside inhibitor (strobilurin) |
| 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. |
| 7 | Unsure or lacking scientific evidence. For fungicides, this 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). |
Acknowledgment: Adaskaveg et al., 2025. Fungicides, Bactericides, Biocontrols, and Natural Products for Deciduous Tree Fruit and Nut, Citrus, Strawberry, and Vine Crops in California.