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UC Pest Management Guidelines

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Prune (Dried Plums)

2010 Fungicide Efficacy and Treatment Timing

(Reviewed 3/10, updated 3/10)

In this Guideline:

FUNGICIDE EFFICACY FOR PRUNE (DRIED PLUM) DISEASES

Fungicide Resistance risk (FRAC#)1 Brown rot Russet scab Rust
Blossom Fruit2
Adament2,7 medium (3/11) ++++ ++++ ---- +++
Bumper/Tilt2 high (3) ++++ ++++ ---- +++
Distinguish** medium (9/11) ++++ ++ ---- ++
Elite/Tebuzol2,7 high (3) ++++ ++++ ---- +++
Indar2 high (3) ++++ ++++ ---- +++
Inspire*2 high (3) ++++ ++++ ---- +++
Inspire Super* high (3/9) ++++ ++++ ---- +++
Luna Sensation*2 medium (7/11)4 ++++ ++++ ND ND
Pristine2 medium (7/11)4 ++++ ++++ ND ND
Quash* 2 high (3) ++++ ++++ ---- +++
Quadris Top*2 medium (3/11)4 ++++ ++++ ND ++++
Quilt Xcel*2 medium (3/11)4 ++++ ++++ ND ++++
Rovral + oil2,5 low (2) ++++ NR ---- NR
Scala6 high (9)3,4 ++++ +++6 ---- ND
Topsin-M /T-Methyl/Thiophanate-Methyl + oil2,4 high (1)4 ++++ ++++ ---- ----
Vangard6 high (9)3,4 ++++ +++6 ---- ND
Elevate2,7 high (17)4 +++ +++ ND ----
Rovral/Iprodione /Nevado2 low (2) +++ NR ---- NR
Topsin-M/T-Methyl/Thiophanate-Methyl 2,3 high (1)4 +++ +/- ---- ----
Abound high (11)4 ++ + ---- +++
Botran medium (14) ++ ++ ND ND
Bravo/Chlorothalonil/Echo/Equus8,9,10 low (M5) ++ ++ ++ ----9
Captan7,8,10 low (M4) ++ ++ +++ ----
Gem7 high (11)4 ++ + ---- +++
Rally2 high (3) ++ ++ ---- ----
Sulfur10 low (M2) +/- +/- ---- ++
Rating: ++++= excellent and consistent, +++= good and reliable, ++= moderate and variable, += limited and erratic, +/- = minimal and often ineffective, ---- = ineffective, ? = insufficient data or unknown, NR=not registered after bloom, 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** Not registered, label withdrawn or inactive.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 Fruit brown rot treatments for fungicides in FRAC Groups 1,2, 3, 17, 7/11 are improved with the addition of 2% light summer oil. The oil is "light" summer oil (1-2% vol/vol). If applied in summer, fruit will loose their waxy bloom and look red. They will dry to normal color.
3 Strains of Monilinia fructicola and M. laxa resistant to Topsin-M and T-Methyl have been reported in some California prune orchards.  No more than two applications of Topsin-M or T-Methyl should be made each year. 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 prune with overuse of fungicides with similar chemistry. Subpopulations of both Monilinia spp. have been shown to be resistant to AP (FRAC 9) fungicides on prune in CA.
4 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.
5 Blossom blight only; not registered for use after petal fall.
6 High summer temperatures and relative humidity reduce efficacy.
7 Registered for use on fresh prunes only.
8 Do not use in combination with or shortly before or after oil treatment.
9 Do not use after jacket (shuck) split.
10 Do not use sulfur, captan, or chlorothalonil in combination with or shortly before or after oil treatment.

FUNGICIDE TREATMENT TIMING IN PRUNE (DRIED PLUM)

Note: Timings listed are effective but not all may be required for disease control. Timings used will depend upon orchard history of disease, length of bloom, and weather conditions each year.
Disease Green bud White bud Full bloom May June July
Brown rot1 +++ +++ +++ ---- + ++
Russet scab2 ---- ---- +++ ---- ---- ----
Rust3 ---- ---- ---- + ++ +++
Rating: +++ = most effective, ++ = moderately effective, + = least effective, and ---- = ineffective.
1 Flowers are susceptible beginning with the emergence of the sepals (green bud) until the petals fall, but are most susceptible when open.
2 A physiological disorder, no pathogens involved.
3 More severe when late spring rains occur.

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: Prune
UC ANR Publication 3464
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