Agriculture: Pistachio Pest Management Guidelines

General Properties of Fungicides Used in Pistachios

Common name
(example trade name)
Chemical class
(FRAC group number # )1
Activity Mode of action Resistance potential
azoxystrobin (Abound) QoI2 (11) contact, systemic single-site high7
boscalid (Endura) SDHI4 (7) contact single-site high7
cyprodinil (Vangard) anilinopyrimidine (9) mostly contact, slightly systemic (on most crops) single-site high7
cyprodinil/fludioxonil (Switch) anilinopyrimidine/phenylpyrrole (9/12) contact, slightly systemic single-site/single-site medium to high
fenhexamid (Elevate) hydroxyanilide (17) contact single-site high7
iprodione (Rovral) dicarboximide (2) systemic (local) single-site? medium
pyraclostrobin (Cabrio) QoI2 (11) contact, systemic single-site high7
pyrimethanil (Scala) anilinopyrimidine (9) mostly contact, slightly systemic (on most crops) single-site high7
Reynoutria sachalinensis extract natural product (BM 01,
P05)
contact various low
tebuconazole (Elite) DMI3-triazole (3) systemic (local)6 single-site high
thiophanate-methyl (Topsin-M) MBC5 (1) systemic (local) single-site high to very high7
trifloxystrobin (Gem) Qol2 (11) contact, systemic6 single-site high7
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   QoI = quinone outside inhibitor (strobilurin).
3   DMI = demethylation (sterol) inhibitor.
4   SDHI = succinate dehydrogenase inhibitor
5   MBC = methyl benzimidazole carbamate
6   Generally considered to have systemic action based on performance data but has not been proven experimentally.
7   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: 10/14