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How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

Almond

2008 Fungicide Efficacy and Treatment Timing

(Reviewed 2/08, updated 2/08)

In this Guideline:

FUNGICIDE EFFICACY FOR ALMONDS DISEASES

Fungicide Resistance risk (FRAC#)1 Brown rot Jacket rot Anthracnose Shot hole Scab2 Rust3 Leaf blight Alternaria leaf spot 2 PM-like4 Silver leaf
Adament high (3/11) ++++ ++ ++++ ++ +++ +++ ND ++ ND —
Benlate5 high (1) ++++ ++++ — — +++ + ++++6 — — —
Distinguish high (9/11) ++++ +++ ++++ ++ ND ND ND ND ND —
Indar high (3) ++++ +/- +++ ++ ++ +++ ND + ND —
Inspire* high (3) ++++ + ND ++ +++ ND ND +++ ND —
Inspire Super16 high (3/9) ++++ ++ ND ++ +++ ND ND +++ ND —
Orbit high (3) ++++ +/- ++++ ++ ++ +++ ND ++ ND —
Pristine3 medium (7/11) 7 ++++ ++++ ++++ ++++ ++++ +++ ND +++ +++ —
Quash high (3) ++++ ++ ++++ +++ ND ND ND ++ ND —
Rovral + oil8 low (2) ++++ ++++ — +++ +/- ++ ND +++9 ND —
Scala high (9) 7 ++++ ++++ ND ++ — ND ND NR — —
Topsin-M/T-Methyl5 high (1)7 ++++ ++++ — — +++8 + +++6 — ++ —
Vangard high (9) 7 ++++ ++++ ND ++ — ND ND +9 — —
Abound high (11) 7 +++ — ++++ +++ ++++ +++ +++ +++10 +++ —
Elevate high (17) 7 +++ ++++ — + ND ND ND ND ND —
Gem high (11) 7 +++ — ++++ +++ ++++ +++ +++ +++10 +++ —
Laredo high (3) +++ — ++ ++ — + +++ — +++ —
Rovral/Iprodione low (2) +++ +++ — +++ — — ND ++9 — —
Bravo/Chorothalonil/Echo11,12 low (M5) ++ NR +++ +++ +++ NR NR NR — —
Captan12 low (M4) ++ ++ +++ +++ ++ — +++ + — —
Captevate low (M4/17) +++ +++ +++ +++ +++ — +++ + — —
Maneb low (M3) ++ + ++ ++ ++ +++ ++ — — —
Ph-D medium (19) ++ ++ — ++ — ND ND +++ — —
Rally13 high (3) ++ — ++ +/- — + +++ — +++ —
Ziram low (M3) ++ + +++ +++ +++ — ++ + — —
Copper14 low (M1) +/- +/- — + 6 — — — ND — ND
Lime sulfur12 low (M2) +/- NR — +/- ++15 NR NR NR — NR
Sulfur12 low (M2) +/- +/- — — ++ ++ — — +++ —
PlantShield** low — — — — — — — — — +++16
Rating: ++++ = excellent and consistent, +++ = good and reliable, ++ = moderate and variable, + = limited and/or erratic, +/- = minimal and often ineffective, — = ineffective, NR = not registered, and ND = no data.
* Not registered in California
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 Field resistance of Alternaria sp. and Cladosporium carpophilum to strobilurin and carboxamide fungicides has been detected in almond orchards.
3 Of the materials listed, only sulfur, Abound, and Flint are registered for use in late spring and early summer when treatment is recommended.
4 PM-like refers to a powdery mildew-like disease on almond fruit that is managed with fungicides with activity against powdery mildew fungi.
5 Benlate label withdrawn. Strains of the brown rot fungi Monilinia laxa and M. fructicola resistant to Benlate, Topsin-M, and T-Methyl have been found 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 almonds with overuse of fungicides with similar chemistry.  Resistant strains of the scab fungus, Cladosporium carpophilum, have been found in California.
6 Excellent control obtained with combination of Benlate and Captan; activity of Topsin-M and T-Methyl should be similar to that of Benlate.
7 To reduce the risk of resistance development start treatments with a fungicide with a multi-site mode of action; rotate or mix fungicides with different mode of action FRAC numbers for subsequent applications, use labeled rates (preferably the upper range), and limit the total number of applications/season.
8 Oil is a “light” summer oil, 1-2% volume/volume.
9 Not registered for use later than 5 weeks after petal fall.
10 Efficacy reduced at high temperatures and relative humidity; experimental for Alternaria.
11 Bravo Ultrex, Bravo WeatherStik, Echo, Echo Ultimate, and Chlorothalonil are currently registered.
12 Do not use in combination with or shortly before or after oil treatment.
13 Efficacy is better in concentrate (80-100 gal/acre) than in dilute sprays.
14  The low rates necessary to avoid phytotoxicity in spring reduce the efficacy of copper.
15 "Burns out" scab twig lesions when applied at delayed dormant.
16 Registration pending.

FUNGICIDE TREATMENT TIMING IN ALMONDS

Note: Not all indicated timings may be necessary for disease control.
Disease Dormant Bloom Spring1 Summer
Pink bud Full bloom Petal fall 2 weeks 5 weeks May June
Alternaria — — — — — +++ +++ +++
Anthracnose2 — ++ +++ +++ +++ +++ +++ ++
Brown rot — ++ +++ + — — — —
Green fruit rot — — +++ — — — — —
Leaf blight — — +++ ++ + — — —
Scab3 + — — ++ +++ +++ ++ —
Shot hole4 +5 + ++ +++ +++ ++ — —
Rust — — — — — +++ +++ +6
Rating: +++ = most effective, ++ = moderately effective, + = least effective, and — = ineffective.
1. Two and five weeks after petal fall are general timings to represent early postbloom and the latest time that most fungicides can be applied. The exact timing is not critical but depends on the occurrence of rainfall.
2. If anthracnose was damaging in previous years and temperatures are moderate (63°F or higher) during bloom, make the first application at pink bud. Otherwise treatment can begin at or shortly after petal fall. In all cases, application should be repeated at 7- to 10-day intervals when rains occur during periods of moderate temperatures. Treatment should, if possible, precede any late spring and early summer rains. Rotate fungicides, using different fungicide classes, as a resistance management strategy.
3. Early treatments (during bloom) have minimal effect on scab; the 5-week treatment usually is most effective. Treatments after 5 weeks are useful in northern areas where late spring and early summer rains occur. Dormant treatment with liquid lime sulfur improves efficacy of spring control programs.
4. If pathogen spores were found during fall leaf monitoring, apply a shot hole fungicide during bloom, preferably at petal fall or when young leaves first appear. Re-apply when spores are found on new leaves or if heavy, persistent spring rains occur. If pathogen spores were not present the previous fall, shot hole control may be delayed until spores are seen on new leaves in spring.
5. Dormant copper treatment seldom reduces shot hole infection but may be useful in severely affected orchards and must be followed by a good spring program.
6. Treatment in June is important only if late spring and early summer rains occur.
Adapted from:
Adaskaveg, J. E., B. A. Holtz, T. J. Michailides, and W. D. Gubler. 2008. Efficacy and Timing of Fungicides, Bactericides, and Biologicals for Deciduous Tree Fruit, Nut, Strawberry, and Vine Crops (932 KB, PDF)

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PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Almond
UC ANR Publication 3431
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Statewide IPM Program, Agriculture and Natural Resources, University of California
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