Fungicide Resistance Management

Note: Not all indicated timings may be necessary for disease control: see MOST EFFECTIVE TREATMENT TIMINGS FOR KEY DISEASES. If treatments are needed based on weather monitoring or environmental monitoring models, suggested fungicide groups are listed for each timing.

HOW TO USE THIS TABLE

1.    Identify the disease(s) that need(s) to be managed. Know the disease history of the orchard, especially from the previous season.
2.    Select one of the suggested FRAC1 mode-of-action group numbers. Numbers separated by slashes are pre-mixtures, whereas numbers grouped by pluses are tank mixtures. If several diseases need to be managed, select a group that is effective against all diseases. Refer to GENERAL PROPERTIES OF FUNGICIDES table for fungicides belonging to each FRAC1 group. Group numbers are listed in numerical order within the suggested disease management program.
3.   Rotate groups for each application within a season and, if possible, use each group only once per season, except for multi-site mode of action materials, or natural products or biological controls (e.g., M2, BM 01, BM 02, NC).

FRAC¹ Group Numbers Suggested for Disease Management Program

Disease	Dormant	Prebloom	White Tip/Popcorn	Full bloom	Petal fall	2–3 weeks later	Preharvest 1–10 days
Botrytis blossom blight or Gray mold fruit decay	—	—	13, 2+oil, 34	13, 2+oil, 34, 3/7, 3/11 3+17, 7/11, 17, 19	2+oil, 3/7, 7, 7/11, 17, 19	—	34, 3/7, 3+17 7/11, 17, 19
Brown rot blossom blight or Fruit rot	—	—	13, 2+oil 3, 3/11, 7, 19	13, 3, 7, 3/7 3+17, 3/11 7/11, 17, 19	—	—	3, 3/7, 3/11, 7, 7/11, 17, 19
Powdery mildew	M22	M22	2+oil, 3	13, 3, 3/7, 3/11, 7, 7/11, 13, 19, BM 01, BM 02, NC	3, 3/7, 7, 7/11, 11, 13, 19, M22, BM 01, BM 02, NC	3, 3/7, 3/11, 7, 7/11, 11, 13, 19, M22, BM 01, BM 02, NC	3, 3/7, 3/11 3+17, 7/11, 11, 19, BM 01, BM 02, NC

1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions. Group numbers are listed in numerical order within the suggested disease management program. Fungicides with a different group number are suitable to alternate in a resistance management program. Refer to the fungicide efficacy table for fungicides belonging to each FRAC group. FRAC group for soft chemistries: potassium bicarbonate (e.g., Kaligreen, Milstop FC NC), fermentation product (FC 19 – e.g., Oso), Streptomyces lydicus (e.g., Actinovate AG – FC BM 02), Bacillus amyloliquefaciens Strain MBI 600 (e.g., Serifel – FC BM 02), and Bacillus amyloliquefaciens Strain QST 713 (e.g., Serenade – FC BM 02). In general, sulfur compounds (FC M2) are fungicidal and may affect applications of fungal biocontrols (e.g., Blossom Protect); whereas copper may affect applications of bacterial biocontrols (e.g., Actinovate, Double Nickel 55, and Serenade). Rotations of products must consider these factors.

2 Use liquid lime sulfur in dormant applications and wettable sulfur at and after prebloom.

3 Strains of Monilinia fructicola resistant to Topsin-M, and T-Methyl are present in some California cherry orchards. Resistant strains of the jacket rot fungus, Botrytis cinerea, and powdery mildew fungi have been reported in California on crops other than almond and stone fruits and may have the potential to develop in sweet cherry with overuse of fungicides with similar chemistry.

4 Among the group 3 fungicides, Elite//Orius and Quash have some activity against Botrytis cinerea.

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)