| Common name (Example trade name) |
Chemical class | Activity | Mode of action (group number)1 |
Resistance potential | Comments |
|---|---|---|---|---|---|
| PREHARVEST | |||||
| azoxystrobin (Abound) | Qol2 (strobilurin) | contact and systemic | single-site (11) | high7 | |
| azoxystrobin/difenoconazole (Quadris Top) | QoI2/DMI3 | contact and systemic (local) | single-site/ single-site (3/11) |
medium | premixture |
| Bordeaux | inorganic | contact | multi-site (M1) | low | copper and lime based mixture that often includes a zinc adjuvant. |
| copper | inorganic | contact | multi-site (M1) | low | fixed coppers (non-copper sulfate materials such as copper hydroxide and copper oxide) |
| fluopyram/trifloxystrobin (Luna Sensation) |
SDHI4/QoI2 | contact and systemic | single-site/ single-site (7/11) |
medium to high | premixture |
| fluxapyroxad/pyraclostrobin (Priaxor) | SDHI4/QoI2 | contact and systemic | single-site/ single-site (7/11) |
medium to high | premixture |
| fosetyl-al (Aliette) | phosphonate | systemic | unknown (P07, 33) | low to medium | resistant pathogen populations reported |
| hydrated lime | inorganic | contact | multi-site (M1) | low | |
| mefenoxam (Ridomil Gold) | phenylamide | contact and systemic | single-site (4) | high7 | |
| oxathiapiprolin (Orondis) | oxysterol binding proteins | contact—fruit/ systemic (local)—roots | single-site (49) | high | |
| oxytetracycline (Fireline) | antibiotic | contact | protein synthesis (41) | high | |
| polyoxin-D (Tavano/Oso) | polyoxin | contact | single-site (19) | medium | biopesticide |
| potassium phosphite (Fungi-Phite, Prophyt) | phosphonate | systemic | unknown (multi-site?) (P07, 33) | low to medium | biopesticide, resistant pathogen populations reported |
| streptomycin (Firewall) | antibiotic | systemic | protein synthesis (25) | high | |
| POSTHARVEST | |||||
| fludioxonil (Graduate) | phenylpyrrole | contact | single-site (oligo-site) (12) | medium | |
| fludioxonil/azoxystrobin (Graduate A+) | phenylpyrrole/Qol2 (strobilurin) | contact/locally systemic | few (multi-site) (11/12) | medium | premixture |
| imazalil (FungaFlor 500EC) | DMI3 | systemic (local) | single-site (3) | high | resistant pathogen populations reported |
| pyrimethanil (Penbotec) | AP5 | mostly contact, slightly systemic (on most crops) | single-site (9) | high7 | resistant pathogen populations reported |
| 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 inhibitors |
| 4 SDHI = Succinate dehydrogenase inhibitors |
| 5 AP = Anilinopyrimidine |
| 6 MBC = methylbenzimidazole carbamate |
| 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., 2022. Fungicides, Bactericides, Biocontrols, and Natural Products for Deciduous Tree Fruit and Nut, Citrus, Strawberry, and Vine Crops in California. (PDF)