| Pesticide | Resistance risk (FRAC group number)1 |
Walnut blight2 | Anthracnose | Botryosphaeria blight*** | Kernel mold*** |
|---|---|---|---|---|---|
| Bactericides | |||||
| Bordeaux2 | low (M1) | 4 | 0 | 0 | 0 |
| Copper + mancozeb (Manzate, Dithane) | low (M1 + M3) | 5 | 5 | 3(2) | 0 |
| Copper + mancozeb + surfactant4 | low (M1 + M3) | 2 | ND | ND | 0 |
| Fixed coppers2,3 | medium (M1) | 4 | 0 | 0 | 0 |
| Kasumin | high (24) | 4 | 0 | 0 | 0 |
| Kasumin + copper | low (24 + M1) | 5 | 0 | 0 | 0 |
| Kasumin + mancozeb | low (24 + M3) | 5 | 0 | 0 | 0 |
| Syllit + copper | high (U12 + M3) | 4 | ND | 0 | 0 |
| Syllit + Kasumin | high (U12 + 24) | 4 | ND | 0 | 0 |
| Zinc sulfate + copper + hydrated lime (Zinc Bordeaux) |
low (M1) | 4 | 0 | ND | 0 |
| Fungicides | |||||
| Abound | high (11) | 0 | ND | ND | ND |
| Cevya | high (3) | 0 | ND | 4 | ND |
| Fontelis | high (7) | 0 | ND | 4 | ND |
| K-Phite3 | low (P07, 33) | 2 | ND | 5 | ND |
| Luna Experience | medium (3/7) | 0 | 5 | 5 | ND |
| Luna Experience + Regalia | medium (3/7 + (BM 01, P 05) | 3 | 5 | 5 | ND |
| Luna Privilege | high (7) | 0 | ND | ND | ND |
| Luna Sensation | medium (7/11) | 0 | 5 | 5 | ND |
| Merivon | medium (7/11) | 0 | 5 | 5 | 3 |
| Miravis Duo | medium (3/7) | 0 | ND | 4 | ND |
| Ph-D | medium (19) | 0 | 5 | 4 | ND |
| Pristine | medium (7/11) | 0 | 5 | 5 | ND |
| Quadris Top | medium (3/11) | 0 | 5 | 4 | ND |
| Quash | high (3) | 0 | 5 | 5 | ND |
| Quilt Xcel | medium (3/11) | 0 | 5 | 5 | ND |
| Rhyme | high (3) | 0 | 5 | ND | 3 |
| Teb, Tebuconazole, Toledo | high (3) | 0 | ND | 4 | 3 |
| Viathon | medium (3/P07, 33) | ND | ND | 4 | ND |
| 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. |
| *** Research is ongoing to determine the most efficacious materials and the optimum timing of treatments for management of botryosphaeria blight and kernel mold of walnut. Fungicides rated for kernel mold may have to be mixed (e.g., Merivon—FRAC group 7/11 and Teb—FRAC group 3) and rotated to another fungicide (e.g., Rhyme—FRAC group 3). This mixture rotation is 4 (good and reliable). |
| 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. |
| 4 A single application with a surfactant is not recommended because of buildup of populations on buds that may increase disease in subsequent years. |
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)