WSU Extension


Crown gall 
European canker (Nectria canker) 
Fire blight 
Pacific Coast pear rust 
Pear trellis rust 
Powdery mildew 
Pseudomonas blossom blast and dieback 
Stony pit 
Virus diseases 
Apple-and-thorn skeletonizer 
Brown marmorated stink bug 
Codling moth 
Cutworms and armyworms 
Pear psylla 
Pear slug (pear sawfly) 
Pearleaf blister mite 
San Jose scale 
Spider mites 

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Caption: Pear stony pit virus symptoms
Photo by: R.S. Byther
Pear : Stony pit
(revision date: 5/20/2014)

Stony pit is a virus disease of pears apparently spread by vegetative propagation (budding, grafting, rooting cuttings). Insects are not known to carry the virus. The disease primarily affects the fruit. Dark green areas appear on young fruit. The areas become pitted, with tissue in the pits becoming hardened and sometimes dying. Affected fruits may be mildly to severely deformed. Severity of the disease varies from fruit to fruit and from year to year. Young leaves of infected trees may show a faint mottling and bark may be "pimpled" or cracked. Severe symptoms have been seen on the cultivars 'Bosc', 'Comice', and 'Seckel'.
Management Options

Non-Chemical Management
  • Remove infected trees.
  • Plant and propagate using only certified virus-free materials.
Select non-chemical management options as your first choice!

Chemical Management

None recommended


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Caption: Pear stony pit virus symptoms
Photo by: R.S. Byther