Agriculture: Walnut Pest Management Guidelines

General Properties of Fungicides Used in Walnuts

Common name (Example trade name) Chemical class1 Mode of action (FRAC1 No.) Activity Resistance potential Comments
azoxystrobin / difenoconazole (Quadris Top) QoI2 / DMI3 single-site / single-site (11/3) contact, systemic (local) medium  
azoxystrobin / propiconazole (Quilt Xcel) QoI2 / DMI3 single-site / single-site (11/3) contact, systemic (local) medium  
copper inorganic multi-site (M1) contact low  
difenoconazole / cyprodinil (Inspire Super) DMI2/AP7 single-site / single-site (3/9) contact, systemic (local) medium  
fluopyram / tebuconazole (Luna Experience) SDHI4 pyridinyl-ethyl-benzamide / DMI3 single-site / single-site (7/3) contact, systemic (local) medium  
fluopyram / trifloxystrobin (Luna Sensation) SDHI4 pyridinyl-ethyl-benzamide / QoI2 single-site / single-site (7/11) contact, systemic (local) high  
flutriafol (Rhyme) DMI3 single-site (3) systemic (local) high  
mancozeb (Dithane, Manzate) carbamate (EBDC) 5 multi-site (M3) contact low  
mefenoxam (Ridomil Gold) acylalanine single-site (4) contact, systemic (local) high  
metconazole (Quash) DMI3 single-site (3) systemic (local) high  
penthiopyrad (Fontelis) SDHI4 pyrazole-4-carboxamide single-site (7) contact, systemic (local) high  
phosphorous acid (Fosphite) phosphonates multi-site? (33) systemic low  
polyoxin-D (Ph-D) polyoxin single-site (19) contact medium  
pyraclostrobin / boscalid
(Pristine)
Qol3 / SDHI4 pyridine-carboxamide / Qol2 single-site / single-site (11/7) contact, systemic (local) high  
pyraclostrobin / fluxapyroxad (Merivon) Qol3/SDHI4 pyrazole-4-carboxamide single-site / single-site (11/7) contact, systemic (local) high  
tebuconazole (Tebuzol) DMI-triazole single-site (3) systemic (local) high  
Rating: +++ = most effective, ++ = moderately effective, + = inconsistently effective, ---- = ineffective, and ND= no data.
1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions. Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode-of-action group numbers 1, 4, 9, 11, 17, or 19 before rotating to a fungicide with a different mode-of-action group number; for fungicides with other group numbers, make no more than two consecutive applications before rotating to fungicide with a different mode-of-action group number.
2 QoI = quinone outside inhibitor or strobilurin
3 DMI = demethylation (sterol) inhibitor
4 SDHI = succinate dehydrogenase inhibitor
5 EBDC = ethylene bisdithiocarbamate
6 MBC = methyl benzimidazole carbamate
7 AP = anilinopyrimidine

Acknowledgment: Adaskaveg et al., 2017. Efficacy and Timing of Fungicides, Bactericides, and Biologicals for Deciduous Tree Fruit, Nut, Strawberry, and Vine Crops (PDF)

Text Updated: 06/17