How to Manage Pests

UC Pest Management Guidelines

Pear

2017 Fungicide Efficacy and Treatment Timing

(Reviewed 6/17 , updated 6/17 )

In this Guideline:


FUNGICIDE EFFICACY — Conventional Chemistry

Fungicide Resistance risk (FRAC#)1 Scab
Protectant Eradicant
Flint2 high (11)3 ++++ ++++
Fontelis high (7) ++++ ++
Luna Sensation medium (7/11) ++++ ++
Inspire Super medium (3/9) ++++ ++++
Merivon medium (7/11) ++++ ++
Pristine medium (7/11) ++++ ----
Procure4 high (3) ++++ ++++
Rally5 high (3) ++++ ++
Rubigan**, Vintage**4 high (3) ++++ ++++
Rhyme, Topguard5 high (3) ++++ ++
Captan6 low (M4) +++ ----
Dithane, Manzate, Penncozeb6 low (M3) +++ ----
Scala high (9)3 +++ +++
Sovran high (11)3 +++ +++
Syllit medium (U12) +++ +++
Tebucon, Toledo high (3) +++ +++
Topsin-M, T-Methyl, Incognito, Cercobin3 high (1)3 +++ +++
Vangard high (9)3 +++ +++
Copper6 low (M1) ++7 ----
Lime sulfur6,8 low (M2) ++ ++++8
Ph-D, Oso high (19) ++ ----
Sulfur7 low (M2) ++ ----
Ziram6 low (M3) ++ ----

FUNGICIDE EFFICACY – Soft Chemistry (Biologicals and Natural Products)

Fungicide Resistance risk (FRAC#)1 Scab
Protectant Eradicant
Lime sulfur low (M2) ++ ----
Sulfur7 low (M2) ++ ----
Actinovate low (Bio-1)13 +/++ ----
Blight Ban low (Bio-1)13 +/++ ----
Blossom Protect low (Bio-2)13 +/++ ----
Double Nickel 55 low (Bio-1)13 +/++ ----
Regalia low (Bio-3)13 +/++ ----
Serifel5 low (Bio-1)13 +/++ ----
Serenade low (Bio-1)13 +/++ ----
Copper7 low (M1) +/++ ----

BACTERICIDE EFFICACY – Conventional Chemistry

Bactericide/ Biological Resistance risk Fire blight11 Phytotoxicity Growth Regulator/SAR
Contact Systemic
Ag Streptomycin, Agri-Mycin, Firewall very high (25) ++++ +++ +/- ----
Kasumin* high (24) ++++ ++++ +/- ----
MycoShield, FireLine high (41) +++ +++ +/- ----
Captan6 low (M4) ++ ---- ---- ----
Copper7 low (M1) ++ ---- + ----
Dithane, Manzate, Penncozeb6 low (M3) ++ ---- ---- ----
Actigard12 low (P1) ---- + ---- +12
Apogee5 low ---- ---- ---- ++11

BACTERICIDE EFFICACY – Soft Chemistry (Biologicals and Natural Products)

Bactericide/ Biological Resistance risk Fire blight11 Phytotoxicity Growth Regulator/SAR
Contact Systemic
Blossom Protect low (Bio-2)13 ++ ---- +/- ----
Copper7 low (M1) ++ ---- + ----
Actinovate low (Bio-1)13 +/++ ---- +/- ----
Blight Ban low (Bio-1)13 +/++ ---- +/- ----
Double Nickel 55 low (Bio-1)13 +/++ ---- +/- ----
Regalia low (Bio-3)13 +/++ ---- +/- ----
Sanitizers14 low +/++ ---- ---- ----
Serenade low (Bio-1)13 +/++ ---- +/- ----
Lime sulfur low (M2) ---- ---- +++ ----
Rating:   ++++ = excellent and consistent, +++ = good and reliable, ++ = moderate and variable, + = limited and/or erratic, +/- = minimal and often ineffective, / = variable, ---- = ineffective, ND = no data.
* Registration pending in California.
**Not registered, label withdrawn or inactive in California.
*** Postharvest fruit registrations in California include: TBZ, Alumni, Penbotec, Scholar, and BioSpectra.
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 High resistance potential to trifloxystrobin for apple and pear scab pathogen populations.
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. Cercobin is registered only on apples.
4 On pear, use only before white bud and after full bloom.
5 Labeled on apple only in California.
6 These materials show some efficacy and should be used in mixtures with antibiotics as a component of resistance management programs. Captan is registered on apples, whereas Dithane is registered on apples and pears.
7 Though copper may be effective for scab and blight control under low disease pressure, copper products may cause fruit scarring or russeting.
8 "Burns out" scab twig lesions when applied at delayed dormant and disrupts pseudothecial (or ascostroma) development when applied to leaves in fall. CAUTION: LIME SULFUR IS INCOMPATIBLE WITH MOST OTHER PESTICIDES WHEN USED AFTER BUDBREAK. CHECK BEFORE USE.
9 In-season application eradicates powdery mildew.
10 Labeled on pear but not on apple.
11 Growth regulators such as prohexadione calcium (Apogee) can be used in an integrated approach to reduce host susceptibility but do not have antibiotic activity against fire blight. Thus, Apogee was not included in the fire blight activity ratings.
12 Acibenzolar-S-methyl (FRAC P1) is a host plant defense inducer known to stimulate the salicylic acid pathway.
13 Biologicals (Bio) can be divided into Bio-1, -2, and -3 subgroups based on their active ingredients of bacteria, fungi, and plant extracts, respectively.
14 Sanitizers such peroxyacetic acid (e.g., Oxidate, Zerotol, Perasan A) are oxidizers that act immediately on contact. They are neutralized rapidly by reducing agents and are non-persistent. Note: Zerotol is registered only on apple, but not on pears. Perasan A is for postharvest use in sanitizing fruit only.
15 Higher numbers of +s indicate higher phytotoxicity.

TREATMENT TIMING

Note: Not all indicated timings may be necessary for disease control.
Disease Fall Delayed dormant White bud Full bloom Petal Fall/ Cover Sprays
Scab1 ++2 ++2 +++ +++ +++
Powdery mildew3 ---- ---- ---- +++ +++
Fire blight ---- + ++ +++  +++4
Rating:   +++ = most effective, ++ = moderately effective, + = least effective, and ---- = ineffective
1 Protection of early tissue is important. Additional applications should be made according to infection periods as determined by the Mills table.
2 Disruption of pseudothecial (ascostroma) development (fall) and inactivation of overwintering twig lesions (delayed dormant); effects of these treatments on disease control is uncertain.
3 Early applications are most effective; additional applications are made if mildew continues.
4 Start management program at the beginning of bloom and continue through bloom including "rat-tail" bloom throughout spring. Several models are available for forecasting infection periods and treatment timing. Models include: Maryblyt, Cougar Blight, etc.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Pear
UC ANR Publication 3455

General Information

Acknowledgment: Adaskaveg et al., 2017. Efficacy and Timing of Fungicides, Bactericides, and Biologicals for Deciduous Tree Fruit, Nut, Strawberry, and Vine Crops (PDF).

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