| Bactericide | Resistance risk (FRAC group number)1 |
Fire blight4 | Phytotoxicity4 | Plant growth regulator/SAR | |
|---|---|---|---|---|---|
| Contact | Systemic | ||||
| Actigard5 | low (P 01) | 0 | 2 | 0 | 2 |
| Ag Streptomycin, Agri-Mycin, Firewall | very high (25) | 5 | 4 | 1 | 0 |
| Apogee4 | low (PGR) | 0 | 2/3 | 0 | 3 |
| Captan2 | low (M4) | 3 | 0 | 0 | 0 |
| Copper3 | low (M1) | 3 | 0 | 2 | 0 |
| Dithane, Manzate, Penncozeb2 | low (M3) | 3 | 0 | 0 | 0 |
| Kasumin | high (24) | 5 | 5 | 1 | 0 |
| MycoShield, FireLine | high (41) | 4 | 4 | 1 | 0 |
| Rating: 5 = excellent and consistent, 4 = good and reliable, 3 = moderate and variable, 2 = limited and/or erratic, 1 = minimal and often ineffective, 0 = ineffective. |
| 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 These materials show some efficacy and should be used in mixtures with antibiotics as a component of resistance management programs. Captan is registered on apples, whereas Dithane is registered on apples and pears. |
| 3 Though copper may be effective for scab and blight control under low disease pressure, copper products may cause fruit scarring or russeting. |
| 4 Plant growth regulators (PGR) such as prohexadione calcium (Apogee) can be used in an integrated approach to reduce host susceptibility but do not have antibiotic activity against fire blight. |
| 5 Acibenzolar-S-methyl (FRAC P 01) is a host plant defense or systemic acquired resistance (SAR) inducer known to stimulate the salicylic acid pathway. |
| 6 Higher numbers of indicate higher phytotoxicity. |
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)