Agriculture: Nectarine Pest Management Guidelines

General Properties of Fungicides Used in Nectarines

Common name
(example trade name)
Chemical class Activity Mode of action
(group number)1
Resistance potential Comments
azoxystrobin (Abound) Qol2 contact, systemic7 single-site (11) high8
bordeaux inorganic contact multi-site (M1) low
captan phthalimide contact multi-site (M4) low highly toxic to honey bee larvae
chlorothalonil (Bravo, Echo) chloronitrile contact multi-site (M5) low
copper inorganic contact multi-site (M1) low
cyprodinil (Vangard) anilinopyrimidine mostly contact, slightly systemic (on most crops) single-site (9) high8  
dicloran (Botran) aromatic hydrocarbon contact, systemic single-site (14) medium
fenbuconazole (Indar) DMI3-triazole systemic (local) 7 single-site (3) high
fenhexamid (Elevate) hydroxyanilide contact single-site (17) high8
fosetyl-al (Aliette) ethyl phosphonates systemic unknown (33) low
iprodione (Rovral) dicarboximide systemic (local) single-site?(2) low to medium toxic to honey bee larvae
mefenoxam (Ridomil Gold) phenylamide contact, systemic single-site (4) high8
metconazole (Quash) DMI3-triazole systemic (local) 7 single-site (3) high
myclobutanil (Rally) DMI3-triazole systemic (local) 7 single-site (3) high
propiconazole (Bumper/Tilt) DMI3-triazole systemic (local) 7 single-site (3) high
pyraclostrobin/boscalid (Pristine) Qol2/SDHI5 contact, systemic7 single-site/single-site (11/7) medium to high
pyrimethanil (Scala) anilinopyrimidine mostly contact, slightly systemic (on most crops) single-site (9) high8
quinoxyfen (Quintec) quinoline contact single-site (13) medium to high
sulfur inorganic contact multi-site (M2) low highly toxic to native strains of western predatory mite (Galendromus occidentalis) and to parasites
tebuconazole (Elite) DMI3-triazole systemic (local) 7 single-site (3) high
tebuconazole/trifloxystrobin (Adament) DMI3-triazole/Qol2 contact and systemic (local)7 single-site/
single-site (3/11)
medium to high
thiophanate-methyl (Topsin) MBC6 systemic (local) single-site (1) high to very high8
trifloxystrobin (Gem) Qol2 contact, systemic7 single-site (11) high8
ziram carbamate (DMDC4) contact multi-site (M3) low
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 Qol = quinone outside inhibitor (strobilurin)
3 DMI = demethylation (sterol) inhibitor
4 DMDC = dimethyl dithiocarbamate
5 SDHI = Succinate dehydrogenase inhibitor
6 MBC = Methyl benzimidazole carbamate
7 Fungicide is generally considered to have systemic action based on performance data, but this characteristic has not been necessarily proven experimentally using more rigorous assays (e.g., radioactively labeled compounds).
8 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)

Text Updated: 08/15