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UC Pest Management Guidelines

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Plum

2010 Fungicide Efficacy and Treatment Timing

(Reviewed 3/10, updated 5/10)

In this Guideline:

FUNGICIDE EFFICACY FOR PLUM DISEASES

Note: Spring brown rot and shot hole control is not necessary for most plum cultivars in California.
Fungicide Resistance risk (FRAC#)1 Brown rot Powdery mildew3 Shot hole4
Blossom2 Fruit
Adament medium (3/11)5 ++++ ++++ +++ ND
Bumper/Tilt high (3) ++++ ++++ +++ ND
Distinguish** medium (9/11) ++++ +++ ++ ND
Elite6/Tebuzol6 high (3) ++++ ++++6 +++ ND
Indar high (3) ++++ ++++ +++ ND
Inspire* high (3) ++++ ++++ +++ ND
Inspire Super* high (3/9) ++++ ++++ +++ ND
Luna Sensation* medium (7/11)5 ++++ ++++ +++ ND
Pristine medium (7/11)5 ++++ ++++ +++ ND
Quash high (3) ++++ ++++ +++ ND
Quilt Xcel* medium (3/11)5 ++++ ++++ +++ ND
Quadris Top* medium (3/11)5 ++++ ++++ +++ ND
Rovral7 + oil8 low (2) ++++ NL ---- ND
Scala9 high (9)5,10 ++++ +++9 ND ND
Topsin-M/T-Methyl/ Thiophanate-Methyl5 high (1)5 ++++ ++++ +++ ND
Vangard9 high (9)5,10 ++++ +++9 ND ND
Quintec high (13) ---- ---- ++++ ----
Rally high (3) +++ +++ +++ ND
Rovral/Iprodione/ Nevado7 low (2) +++ NL ---- ND
Abound high (11)5 ++ + ND ND
Botran medium (14) ++ ++ ND ND
Bravo/Chlorothalonil/
Echo/Equus11,12		 low (M5) ++ ++ ---- ND
Captan12 low (M4) ++ ++ ---- ND
Gem high (11)5 ++ ++ ND ND
Copper low (M1) +/- ---- ---- ND
Sulfur12 low (M2) +/- +/- +++ ND
Rating: +++++ = excellent and consistent, +++ = good and reliable, ++ = moderate and variable, + = limited and/or erratic, +/- = minimal and often ineffective, ---- = ineffective, NL = not on label, and ND= no data * Registration pending in California.
*

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** Not registered, label withdrawn or inactive.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 Brown rot blossom blight 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 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 Registered for pre- and postharvest applications on plum.
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 Strains of the brown rot fungus Monilinia fructicola resistant to Topsin-M and T-Methyl 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. Subpopulations of both Monilinia spp. have been shown to be resistant to AP (FRAC 9) fungicides on prune in CA.
11 Do not use after jacket (shuck) split.
12 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.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Plum
UC ANR Publication 3462
General Information
Acknowledgment: Adaskaveg et al., 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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