| Common name (example trade name) |
Chemical class (FRAC group number)1 |
Activity | Mode of action | Resistance potential |
|---|---|---|---|---|
| azoxystrobin (Quadris, Abound discontinued) | QoI2 (11) | contact, systemic6 | single-site | high7 |
| boscalid (Endura) | SDHI4 (7) | contact | single-site | high7 |
| cyprodinil (Vangard) | anilinopyrimidine (9) | contact, systemic on some crops | single-site | high7 |
| cyprodinil/fludioxonil (Switch) | anilinopyrimidine/phenylpyrrole (9/12) | contact, slightly systemic | single-site/single-site | high |
| fenhexamid (Elevate) | hydroxyanilide (17) | contact | single-site | high7 |
| iprodione (Rovral) | dicarboximide (2) | systemic (local) | single-site? | medium |
| pyraclostrobin (Cabrio) | QoI2 (11) | contact, systemic | single-site | high7 |
| pyrimethanil (Scala) | anilinopyrimidine (9) | contact, systemic on some crops | single-site | high7 |
| Reynoutria sachalinensis extract | natural product (P 05) | contact | various | low |
| tebuconazole (Elite**) | DMI3-triazole (3) | systemic (local)6 | single-site | high |
| thiophanate-methyl (Topsin-M) | MBC5 (1) | systemic (local) | single-site | high7 |
| trifloxystrobin (Gem) | Qol2 (11) | contact, systemic6 | single-site | high7 |
| ** | Not registered, label withdrawn or inactive in California |
| 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 | QoI = quinone outside inhibitor (strobilurin). |
| 3 | DMI = demethylation (sterol) inhibitor. |
| 4 | SDHI = succinate dehydrogenase inhibitor |
| 5 | MBC = methyl benzimidazole carbamate |
| 6 | Unsure or lacking scientific evidence. These fungicides are generally considered to have systemic action based on performance data, but may not have been proven using lab assays (e.g. radioactively labeled compounds). |
| 7 | 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., 2025. Fungicides, Bactericides, Biocontrols, and Natural Products for Deciduous Tree Fruit and Nut, Citrus, Strawberry, and Vine Crops in California.