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UC Pest Management Guidelines

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Pistachio

2010 Fungicide Efficacy and Treatment Timing

(Reviewed 3/10, updated 5/10)

In this Guideline:

FUNGICIDE EFFICACY FOR PISTACHIO DISEASES

Fungicide Resistance risk (FRAC#)1 Alternaria late blight Botrytis blossom & shoot blight Botryosphaeria panicle & shoot blight
Adament medium (3/11)3 ++ +++ ++
Abound high (11) 2,3 +++ ---- +++
Bravo low (M5) ++ ---- ++
Bumper/Tilt high (3) ++ + ++5
Cabrio high (11) 2,3 +++ ---- +++
Distinguish** medium (9/11) ++ ++ ----
Chlorothalonil/(Echo**) low (M5) NR ---- NR
Elevate high (17)3 ND ++++ ND
Gem high (11) 2,3 +++ ---- +++
Quash high (3) ++ +++ +++5
Luna Sensation* medium (7/11)3 ++++4 ++++ ++++
Pristine high (7/11)3 ++++4 ++++ ++++
Ph-D* (Polyoxin-D*) medium (19) +++ ---- +++
Quilt Xcel* medium (3/11)3 +++ ---- +++
Scala high (9)3 ++ ++ +++6
Switch high (9/12)3 +++ +++ ++
Tebuzol high (3) +++ + +++5
Topsin-M/T-Methyl/ Thiophanate-Methyl7 high (1) ---- ++ ++
Copper low (M1) + ---- ----
Liquid lime sulfur8 low (M2) ---- ---- +/-
Rating: ++++ = excellent and consistent, +++ = good and reliable, ++ = moderate and variable, + = limited and/or erratic, +/- = minimal and often ineffective, ---- = ineffective, and ND = no data
* Registration pending in California.
** Not registered, label withdrawn or inactive.
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 spp. to Abound and to other strobilurin fungicides (Gem and Cabrio) is widespread in pistachio orchards.
3 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.
4 Resistance to the SDHI (succinate dehydrogenase inhibitor) boscalid has been detected in high levels (80-90%) in some orchards; Pristine should not be applied if resistance to this fungicide is detected in an orchard. Cross-resistance of SDHI fungicides (FRAC Group 7) may occur.
5

Do not apply Bumper/Tilt within 60 days of harvest, Quash within 25 days of harvest, or Tebuzol within 35 days before harvest.
6 Under low and moderate disease pressure.
7 Registered for bloom treatment only; other registered fungicides may also be used at bloom.
8 Dormant treatment only.

FUNGICIDE TREATMENT TIMING IN PISTACHIO

Disease Dormant April May June1 July August2
Alternaria3 ---- ---- ---- +++ +++1 ++
Botryosphaeria4 + +++5 +++5 +++ +++ ++
Botrytis ---- +++ ---- ---- ---- ----
Rating: +++ = most effective, ++ = moderately effective, + = least effective, and ---- = ineffective
1 If only one application is done, the best timing is late June to early July.
2 Sprays not later than the first week in August.
3 Three applications during the season are recommended.
4 Treat once at bloom when the terminals on female trees are 1-2 inches long.  Begin summer applications in late May or early June.  Treat at 2-3 week intervals until mid-August.  For resistance management, do not apply consecutive applications of any strobilurin (Abound, Flint/Gem or Cabrio) or strobilurin-containing fungicides (Pristine), and make no more than two applications of a strobilurin or strobilurin-containing fungicide per season.
5 Early season sprays timed before and/or after rains are effective timings in April and May.
Adaskaveg, J. E., B. A. Holtz, T. J. Michailides, and W. D. Gubler. 2010. Efficacy and Timing of Fungicides, Bactericides, and Biologicals for Deciduous Tree Fruit, Nut, Strawberry, and Vine Crops (1.1 MB, PDF)

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PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Pistachio
UC ANR Publication 3461
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