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How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

Prune (Dried Plums)

2009 Fungicide Efficacy and Treatment Timing

(Reviewed 3/09, updated 3/09)

In this Guideline:

FUNGICIDE EFFICACY FOR PRUNE (DRIED PLUM) DISEASES

Fungicide Resistance risk (FRAC#)1 Brown rot Russet scab Rust
Blossom Fruit2
Benlate3 + oil4 high (1) ++++ ++++ ---- ----
Distinguish* medium (9/11) ++++ ++ ---- ++
Elite* high (3) ++++ ++++ ---- +++
Indar high (3) ++++ ++++ ---- +++
Orbit (Bumper) high (3) ++++ ++++ ---- +++
Pristine medium (7/11)5 ++++ ++++ ND ND
Rovral6 + oil4 low (2) ++++ NR ---- NR
Scala high (9)5 ++++ +++7 ---- ND
Topsin-M3+ oil4 high (1)5 ++++ ++++ ---- ----
Vangard high (9)5 ++++ +++7 ---- ND
Benlate3 high (1) +++ +/- ---- ----
Elevate8 high (17)5 +++ +++ ND ----
Rovral/Iprodione /Nevado5 low (2) +++ NR ---- NR
Topsin-M/T-Methyl/ Thiophanate-Methyl3 high (1)5 +++ +/- ---- ----
Abound high (11)5 ++ + ---- +++
Botran medium (14) ++ ++ ND ND
Bravo/Chlorothalonil/Echo/Equus9,10 low (M5) ++ ++ ++ ----10
Captan9 low (M4) ++ ++ +++ ----
Gem high (11)5 ++ + ---- +++
Rally high (3) ++ ++ ---- ----
Sulfur 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.
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 2, 3, 17, 7/11 are improved with the addition of 2% light summer oil.
3 Strains of Monilinia fructicola and M. laxa resistant to Benlate (label withdrawn), Topsin-M, and T-Methyl have been reported in some California prune orchards. No more than two applications of Benlate and Topsin 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.
4 The oil is "light" summer oil, 1-2% volume/volume. If applied in summer causes fruit to lose bloom and look red. They dry to normal color.
5 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.
6 Blossom blight only; not registered for use after petal fall.
7 High summer temperatures and relative humidity reduce efficacy.
8 Registered for use on fresh prunes only.
9 Do not use in combination with or shortly before or after oil treatment.
10 Do not use after jacket (shuck) split.

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.
Timings used will depend upon orchard history of disease, length of bloom, and weather conditions each year.
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. 2009. Efficacy and Timing of Fungicides, Bactericides, and Biologicals for Deciduous Tree Fruit, Nut, Strawberry, and Vine Crops (960 KB, PDF)

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Prune
UC ANR Publication 3464
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Statewide IPM Program, Agriculture and Natural Resources, University of California
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