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How to Manage Pests

UC Pest Management Guidelines

| More pests | More crops | About guidelines |

Pear

2008 Fungicide Efficacy and Treatment Timing

(Reviewed 2/08, updated 2/08)

In this Guideline:

FUNGICIDE EFFICACY FOR PEARS DISEASES

Fungicide Resistance risk (FRAC#)1 Scab
Protectant Eradicant
Bayleton high (3) — —
Benlate2 high (1) +++ +++
Distinguish* medium (9/11) +++ +++
Flint3 high (11)4 ++++ ++++
Pristine medium (11/7) ++++ —
Procure5 high (3) ++++ ++++
Rally6 high (3) ++++ ++
Rubigan5 high (3) ++++ ++++
Scala high (9)4 +++ +++
Sovran high (11)4 +++ +++
Syllit medium (M7) +++ +++
Topsin-M/ T-Methyl4 high (1)4 +++ +++
Vangard high (9)4 +++ +++
Captan7 low (M4) +++ —
Dithane7 low (M3) +++ —
Maneb6,7 low (M3) +++ —
Thiram6 low (M3) ++ —
Ziram7 low (M3) ++ —
Copper7 low (M1) ++8 —
Lime sulfur7,9 low (M2) — ++++9
Sulfur7 low (M2) ++ —
  Fire blight13  
Bactericide/ Biological Resistance risk Contact Systemic Phytotoxicity
Ag Streptomycin high ++++ +++ +/-
Agri-Mycin high ++++ +++ +/-
MycoShield11 high +++ +++ +/-
Copper8 low +++ — +
Captan7 low (M4) +++ — —
Dithane7 low (M3) +++ — —
Blight Ban low ++ — +/-
Bloomtime Bio12 low +++
(pending registration)		 — +/-
(pending registration)
Rating: ++++ = excellent and consistent, +++ = good and reliable, ++ = moderate and variable, + = limited and/or erratic, +/- = minimal and often ineffective, — = ineffective.
* 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2 Label withdrawn.
3 Label withdrawn on pears because of resistance development.
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 On pear, use only before white bud and after full bloom.
6 Labeled on apple; only the 40WSP formulation is registered on pear in California.
7 These are important components of resistance management programs. Captan is registered on apples, whereas Dithane is registered on apples and pears.
8 Copper, though effective for scab and blight control, causes fruit scarring.
9 "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.
10 In-season application eradicates powdery mildew.
11 Labeled on pear but not on apple.
12 Registration pending in California.
13 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.

FUNGICIDE TREATMENT TIMING IN PEARS

Note: Not all indicated timings may be necessary for disease control.
Disease Fall Delayed dormant Green tip Pink bud Spring
Scab1 ++2 ++2 +++ +++ +++
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 development (fall) and inactivation of overwintering twig lesions (delayed dormant) occurs; effects of these treatments on disease control uncertain.
3. Early application is most effective; added treatments are made if mildew continues.
4. Start management program at the beginning of bloom and continue through bloom including “rat-tail” bloom through out the spring. Several models are available for forecasting infection periods and treatment timing. Models include: Maryblyt, Cougar Blight, etc.
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: Pear
UC ANR Publication 3455
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Statewide IPM Program, Agriculture and Natural Resources, University of California
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