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UC Pest Management Guidelines

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Pear

2010 Fungicide Efficacy and Treatment Timing

(Reviewed 3/10, updated 5/10)

In this Guideline:

FUNGICIDE EFFICACY FOR PEARS DISEASES

Fungicide Resistance risk (FRAC#)1 Scab
Protectant Eradicant
Adament medium (3/11) ++++ ++++
Bayleton high (3) ---- ----
Distinguish** medium (9/11) +++ +++
Inspire Super medium (3/9) ++++ ++++
Flint2 high (11)3 ++++ ++++
Pristine medium (11/7) ++++ ----
Procure4 high (3) ++++ ++++
Rubigan4 high (3) ++++ ++++
Scala high (9)3 +++ +++
Sovran high (11)3 +++ +++
Syllit medium (M7) +++ +++
Tebuzol high (3) +++ +++
Topsin-M/T-Methyl /Thiophanate-Methyl3 high (1)3 +++ +++
Vangard high (9)3 +++ +++
Ph-D* medium (19) + +
Captan6 low (M4) +++ ----
Maneb** low (M3) +++ ----
Thiram5 low (M3) ++ ----
Ziram6 low (M3) ++ ----
Copper6 low (M1) ++7 ----
Lime sulfur6,8 low (M2) ---- ++++8
Sulfur7 low (M2) ++ ----
Bactericide/ Biological Resistance risk Fire blight11 Phytotoxicity
Contact Systemic
Ag Streptomycin/Agri-Mycin/Firewall high ++++ +++ +/-
MycoShield/FireLine10/ FlameOut** high +++ +++ +/-
Copper7 low (M1) +++ ---- +
Captan6 low (M4) ++ ---- ----
Dithane/Manzate/
Penncozeb6		 low (M3) ++ ---- ----
Blight Ban low ++ ---- +/-
Bloomtime Bio low +++ ---- +/-
Rating: ++++ = excellent and consistent, +++ = good and reliable, ++ = moderate and variable, + = limited and/or erratic, +/- = minimal and often ineffective, ---- = ineffective.
* 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** Not registered, label withdrawn or inactive.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2 Label withdrawn on pears because of resistance development.
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.
4 On pear, use only before white bud and after full bloom.
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 Copper, though effective for scab and blight control, causes fruit scarring.
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.

 

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 +++ +++ +++
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 (or ascostroma) 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 throughout the spring. Several models are available for forecasting infection periods and treatment timing. Models include: Maryblyt, Cougar Blight, etc.

Adaskaveg, J. E., B. A. Holtz, T. J. Michailides, and W. D. Gubler. 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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PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Pear
UC ANR Publication 3455
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