| Organic treatments | Resistance risk
(FRAC group number)1 |
Walnut blight2 |
|---|---|---|
| Actinovate | low (BM 02) | 3 |
| Blossom Protect | low (BM 02) | 2/3 |
| Bordeaux2 (organic with approved copper) | low (M1) | 4 |
| Fixed coppers2, 3 (organic with approved copper) | medium (M1) | 4 |
| Regalia | low (BM 01, P 05) | 3 |
| Regalia + Copper (organic with approved copper) | low (BM 01, P 05 + M1) | 3 |
| Serenade (organic) | low (BM 02) | 2 |
| Zinc sulfate + copper + hydrated lime (Zinc Bordeaux) (organic with approved copper) |
low (M1) | 4 |
| 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, NL = not on label, and ND = no data. |
| 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 Copper resistance occurs within sub-populations of Xanthomonas arboricola pv. juglandis. |
| 3 Phytotoxicity may occur. For fixed coppers, injury can be reduced by the addition of lime or agricultural oils to the tank mixture. |
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)