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How to Manage Pests
UC Pest Management Guidelines
Pear
Pear Cankerworms
Scientific names:
Spring cankerworm: Paleacrita vernata
Fall cankerworm: Alsophila pometaria
(Reviewed 2/07,
updated 3/8)
In this Guideline:
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Spring and fall cankerworms were once
major pests of pears when codling moth was controlled with lead arsenate. When
organophosphates were used to control codling moth, they ceased to be a
problem. Using selective materials for codling moth control may cause cankerworms
to become a potential threat. The larvae are typical of the group of worms
called inch or measuring worms. When mature they are about 1 inch long, green
to olive green, with stripes of a different shade of green along the sides.
The larvae are primarily leaf feeders, tending to skeletonize
leaves. Occasionally they feed on young fruit by biting deep holes, which later
heal, but leave large, scarred depressions similar to the injury caused by
green fruitworms. Larvae can be found feeding throughout the tree but tend to
be more numerous along center scaffold limbs.
Cankerworms are potential threats in pear orchards where selective
materials are used for codling moth control. They may be observed in spring
when monitoring leafrollers during bloom (see SAMPLING AT BLOOM).
Follow treatment guidelines for obliquebanded leafroller or omnivorous
leafroller.
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UC IPM Pest Management Guidelines: Pear
UC ANR Publication 3455
Insects and Mites
L. G. Varela, UC IPM Program, UC Cooperative Extension Sonoma Co.
R. B. Elkins, UC Cooperative Extension Lake Co.
R. A. Van Steenwyk, Insect Biology, UC Berkeley
C. Ingels, UC Cooperative Extension Sacramento Co.
Acknowledgment for contributions to the insects and mites section:
C. Pickel, UC IPM Program, UC Cooperative Extension Sutter/Yuba counties
P. W. Weddle, Weddle, Hansen & Associates
P. Chevalier, United Ag Products, Ukiah; B. Knispel, United Ag Products, Kelseyville
T. Lidyoff, Purity Products, Healdsburg; G. McCosker, AgroTech, Kelseyville
B. Oldham, Ag Unlimited, Ukiah
D. Smith, Western Farm Service, Walnut Grove
J. Sisevich, AgroTech, Kelseyville
B. Zoller, The Pear Doctor, Inc., Kelseyville
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