Caution: Never apply sulfur to apricot trees or captan to apricot fruit.
| Common name (Example trade name) |
Chemical class | Activity | Mode of action (FRAC Group No.1) |
Resistance potential | Comments |
|---|---|---|---|---|---|
| azoxystrobin (Quadris, Abound discontinued) | QoI2 | contact, systemic8 | single-site (11) | high9 | |
| captan (Captan) | phthalamide | contact | multi-site (M 04) | low | highly toxic to honey bee larvae |
| chlorothalonil (Bravo, etc.) | chloronitrile | contact | multi-site (M 05) | low | |
| copper10 | inorganic | contact | multi-site (M 01) | low | |
| copper-Bordeaux | inorganic | contact | multi-site (M 01) | low | |
| cyprodinil (Vangard) | anilinopyrimidine | contact, systemic on some crops | single-site (9) | high9 | |
| dicloran (Botran**) | aromatic hydrocarbon | contact, systemic8 | single-site (14) | medium | |
| difenoconazole/cyprodinil (Inspire Super) | DMI4-triazole/ anilinopyrimidine | contact, systemic8 | single-site/single-site (3/9) | medium | |
| difenoconazole/azoxystrobin (Quadris Top) | DMI4-triazole/QoI2 | contact, systemic (local)8 | single-site/single-site (3/11) | medium | |
| fenbuconazole (Indar) | DMI4-triazole | systemic (local)8 | single-site (3) | high | |
| fenhexamid (Elevate) | hydroxyanilide | contact | single-site (17) | high9 | |
| fludioxonil (Scholar) | phenylpyrrole | contact | single-site (12) | medium | postharvest fruit treatment |
| fosetyl-al (Aliette) | phosphonates | systemic | unknown (P 07, 33) | low | |
| iprodione (Rovral, Nevado**, Iprodione) | dicarboximide | systemic (local) | single site? (2) | low | highly toxic to honey bee larvae |
| mefenoxam (Ridomil Gold) | phenylamide | contact, systemic | single-site (4) | high9 | |
| metconazole (Quash) | DMI4-triazole | systemic (local)8 | single-site (3) | high | |
| myclobutanil (Rally) | DMI4-triazole | systemic (local)8 | single-site (3) | high | |
| penthiopyrad (Fontelis) | SDHI7 | contact | single-site (7) | high9 | |
| potassium phosphite (ProPhyt, Fungi-Phite) | phosphorous acid or mono- and dipotassium salts of phosphorous acid3 | systemic | unknown (multi-site?) (P 07, 33) | medium | |
| propiconazole (Bumper ES**, Tilt) | DMI4-triazole | systemic (local)8 | single-site (3) | high | |
| propiconazole/azoxystrobin (Quilt Xcel) | DMI4-triazole/QoI2 | systemic (local)8 | single-site/single-site (3/11) | medium | |
| pyraclostrobin/boscalid (Pristine) | QoI2 /SDHI7 | contact, systemic8 | single-site/single-site (11/7) | medium | |
| pyraclostrobin/fluxapyrozad (Merivon) | QoI2 /SDHI7 | contact, systemic8 | single-site/single-site (11/7) | medium | |
| pyrimethanil (Scala) | anilinopyrimidine | contact, systemic on some crops | single-site (9) | high9 | |
| quinoxyfen (Quintec) | quinoline | contact | single-site (13) | high | |
| tebuconazole (Tebucon, Toledo) | DMI4-triazole | systemic (local)8 | single-site (3) | high | |
| thiophanate-methyl (Topsin-M) | MBC5 | systemic (local) | single-site (1) | high9 | |
| trifloxystrobin (Gem) | Qol2 | contact and systemic8 | single-site (11) | high9 | |
| ziram | carbamate (DMDC6) | contact | multi-site (M 03) | low | highly toxic to honey bee larvae |
| ** | Not registered, label withdrawn or inactive in California (may be 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 | QoI = quinone outside inhibitor (strobilurin) |
| 3 | SAR = systemic acquired resistance induced in host |
| 4 | DMI = demethylation (sterol) inhibitor |
| 5 | MBC= methyl benzimidazole carbamate |
| 6 | DMDC = dimethyl dithiocarbamate |
| 7 | SDHI = succinate dehydrogenase inhibitor |
| 8 | Unsure or lacking scientific evidence. For fungicides, this indicates general acceptance of systemic action based on performance data, but this characteristic may not have been proven experimentally using more rigorous assays (e.g., radioactively labeled compounds). |
| 9 | 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. |
| 10 | Fixed copper (M 01a) bactericides (e.g., Kocide, Badge, Nordox, and ChampION++) may cause phytotoxicity (russetting) when applied after full bloom. Other copper products (M 01b) with lower metallic copper equivalent (i.e., MCE) such as copper complexes (e.g., Cueva, Copper Count-N, etc.) and copper sulfate pentahydrate (e.g., CS-2005, Phyton 27AG, etc.) have been reported to be less phytotoxic with applications following bloom because of lower MCE (see specific registrant label concerning product rates and number of times each material can be applied during the growing 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