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How to Manage Pests

UC Pest Management Guidelines

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Almond

Fungicide Resistance Management

(Reviewed 3/09, updated 6/09)

In this Guideline:

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

How to use this table:

  • Identify the disease(s) that need(s) to be managed. Know the disease history of the orchard especially from the previous season.
  • 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 to determine which fungicides belonging to each FRAC group. Group numbers are listed in numerical order within the suggested disease management program below.
  • Rotate fungicides that have different Group numbers for each application within a season and, if possible, use each Group number only once per season, except for multi-site mode of action fungicides or natural products/biological controls (e.g., M2).
FRAC1 Mode of Action Group Numbers Suggested for Disease Management Program
Disease Dormant Bloom Spring Summer
Pink bud Full bloom Petal fall 2 weeks 5 weeks May June
Alternaria — — — — — 2 3
7/11
11
19 		3
7/11
11
19
Anthracnose — 3 3
7/11
11 		3
11
M3
M4 		3
7/11
11
M3
M4 		3
7/11
11
M3
M4 		3
7/11
11
M3
M4 		3
7/11
11
M3
M4
Brown rot — 12
2 (+oil)
3
9 		12
2 (+oil)
3
9
7/11
11 		12
2 (+oil)
9
7/11 		— — — —
Green fruit rot — — 12
2 (+oil)
9
7/11 		— — — — —
Leaf blight — — 12
2
3
11
12
2
3
11
M3
M4 		3
11
M3
M4 		— — —
Rust — — — — — 3
7/11
11
M3 		3
7/11
11
3
7/11
11
Scab4 M1+oil
M23		 — — 12
7/112
112
M3
M4
M5 		12
7/112
112
M3
M4
M5 		3
7/112
112
M23
M3
M4 		M23
M4		 —
Shot hole M1 2
3
9		 2
3
7/11
9
11		 2
3
7/11
9
11 		7/11
11
M3
M4
M5 		7/11
11
M3
M4
M5 		— —
1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.frac.info/). 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, or 17 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 Strains of Monilinia fructicola and M. laxa resistant to Topsin-M and T-Methyl are present in some California almond 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 almond with overuse of fungicides with similar chemistry.
3 Use liquid lime sulfur in dormant applications and wettable sulfur at and after prebloom.
4 Apply petal fall treatments based on twig-infection sporulation model.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Almond
UC ANR Publication 3431
General Information
F. G. Zalom, Entomology, UC Davis
C. Pickel, UC IPM Program, UC Cooperative Extension, Sutter/Yuba counties
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
D. R. Haviland, UC IPM Program, UC Cooperative Extension, Kern County
R. A. Van Steenwyk, Insect Biology, UC Berkeley
Acknowledgment for contributions to Insects and Mites:
R. E. Rice, Kearney Agricultural Center, Parlier
L. C. Hendricks, UC Cooperative Extension, Merced County
R. L. Coviello, UC Cooperative Extension, Fresno County
M. W. Freeman, UC Cooperative Extension, Fresno County

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