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How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

Plum

2008 Fungicide Efficacy and Treatment Timing

(Reviewed 2/08, updated 2/08)

In this Guideline:

FUNGICIDE EFFICACY FOR PLUM DISEASES

Note: Disease control in spring and preharvest is not necessary for most plum cultivars in California.
Fungicide Resistance risk (FRAC#)1 Brown rot Powdery mildew3 Shot hole4
Blossom2 Fruit
Benlate5 high (1) ++++ ++++ +++ ND
Distinguish* medium (9/11) ++++ +++ ++ ++
Indar high (3) ++++ ++++ +++ ND
Orbit/Bumper high (3) ++++ ++++ +++ ND
Pristine medium (7/11)6 ++++ ++++ +++ ND
Rovral7 + oil8 low (2) ++++ NR — ND
Scala high (9)6 ++++ +++9 ND ND
Topsin-M/T-Methyl5 high (1)6 ++++ ++++ +++ ND
Vangard high (9)6 ++++ +++9 ND ND
Rally high (3) +++ +++ +++ ND
Rovral7 low (2) +++ NR — ND
Abound high (11)6 ++ + ND ND
Botran medium (14) ++ ++ ND ND
Bravo/Chlorothalonil/Echo10,11 low (M5) ++ ++ — ND
Captan11 low (M4) ++ ++ — ND
Gem high (11)6 ++ ++ ND ND
Copper low (M1) +/- — — ND
Sulfur11 low (M2)

 +/- +/- +++ ND
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.
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 Brown rot is seldom observed on most plum cultivars and usually does not require treatment during bloom.
3 Powdery mildew seldom is observed on most plum cultivars and control usually is unnecessary.
4 Shot hole disease rarely occurs on plums in California. The small holes often observed on leaves in spring are caused by either a genetic disorder or by other agents including environmental factors.
5 Benlate label withdrawn. Strains of the brown rot fungus Monilinia fructicola resistant to Benlate and Topsin are found in other stone fruit orchards in California. Brown rot is so seldom found in plum orchards that the resistance levels in plum orchards have not been assessed.
6 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.
7 Blossom blight only; not registered for use after petal fall.
8 The oil is a “light” summer oil, 1-2% volume/volume.
9 High summer temperatures and relative humidity reduce efficacy.
10 Do not use after jacket (shuck) split.
11 Do not use in combination with or shortly before or after oil treatment.

FUNGICIDE TREATMENT TIMING IN PLUMS

Note: Not all indicated timings may be necessary for disease control.
Disease Dormant Green bud Popcorn Full bloom Until pit hardening Preharvest
Brown rot1 — + ++ +++ — +
Powdery mildew — + + +++ +++ —
Shot hole2 — — — — — —
Rating: +++ = most effective, ++ = moderately effective, + = least effective, and — = ineffective.
1. One early application should suffice; a second treatment should not be needed.
2. No treatment is recommended for shot hole because the shot holes found on plum leaves only rarely are caused by the shot hole fungus.

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)

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Plum
UC ANR Publication 34
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Statewide IPM Program, Agriculture and Natural Resources, University of California
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