| Common name (trade name) |
Chemical class (FRAC group number)1 |
Activity | Mode of action | Resistance potential | Comments |
|---|---|---|---|---|---|
| azoxystrobin (Abound) | QoI3 (11) | contact, systemic | single-site | high6 | |
| Bordeaux | inorganic (M1) | contact | multi-site | low | |
| captan | phthalimide (M4) | contact | multi-site | low | highly toxic to honey bee larvae |
| chlorothalonil (Bravo) | chloronitrile (M5) | contact | multi-site | low | |
| copper | inorganic (M1) | contact | multi-site | low | |
| cyprodinil (Vangard) | anilinopyrimidine (9) | mostly contact, slightly systemic (on most crops) | single-site | high6 | |
| fludioxonil (Scholar) | phenylpyrrole (12) | contact | few to multi-sitesingle-site (oligo-site) |
medium | |
| fosetyl-al (Aliette) | ethyl phosphonates (P07/33) | systemic | unknown | low | |
| iprodione (Rovral) | dicarboximide (2) | systemic (local) | single-site? | low to medium | toxic to honey bee larvae |
| mefenoxam (Ridomil Gold) | acylalanine phenylamide (4) | contact, systemic | single-site | high6 | |
| myclobutanil (Rally) | DMI2-triazole (3) | systemic (local) | single-site | high | |
| propiconazole (Bumper/Orbit) | DMI2-triazole (3) | systemic (local) | single-site | high | |
| pyraclostrobin/boscalid (Pristine) | QoI3/SDHI4 (11/7) | contact, systemic | single-site/ single-isite |
medium to high | |
| pyrimethanil (Scala) | anilinopyrimidine (9) | mostly contact, slightly systemic (on most crops)mostly contact | single-site | high6 | |
| sulfur | inorganic (M2) | contact | multi-site | low | highly toxic to native strains of western predatory mite (Galendromus occidentalis) and to parasites |
| thiophanate-methyl (Topsin) | MBC5 (1) | systemic (local) | single-site | high to very high6 |
| 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 QoI = quinone outside inhibitor (strobilurin) |
| 4 SDHI = succinate dehydrogenase inhibitor |
| 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)