Pacific Northwest 1998 An Online Guide to Plant Disease Control

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OSU Extension Office
 
Pear -- Stony Pit
 
Cause: A virus disease carried in scion wood. There is no indication that an insect vector spreads the virus. The disease occurs sporadically in the PNW, apparently in conjunction with specific climatic conditions. Cultivars react differently; only 'Bosc' shows all types of symptoms. Cultivars showing mild symptoms include 'Clairgeau', 'Old Home', 'Packham's Triumph', and 'Waite'. Occasionally, 'Packham's Triumph' fruit show severe symptoms. Studies in the Netherlands suggest that the disease is associated with Apple stem pitting virus.
Symptoms: Under specific climatic conditions, the disease appears in non-certified 'Bosc' and occurs to some extent in 'Anjou' and occasionally in 'Comice' and 'Bartlett', causing a fruit pitting and deformity. Light or moderate fruit symptoms may be confused with pitting from tarnished plant bug damage, boron deficiency, or corky spot. In 'Bosc', a roughened bark condition may also accompany the pitting. There is excessive stone-cell development below the pits in the skin. Pitting may be severe in 'Anjou' but it is less common than in 'Bosc'.

Note the sunken pits on this fruit.

This virus causes misshapen fruit.

 
Cultural control:

  1. Remove and replace with a certified virus-tested (and found to be free of all known viruses) tree.
  2. Establish new plantings only with certified virus-tested trees.
References:
Milbrath, J.A. 1966. Stony Pit of Pear in Oregon. Oregon Agricultural Experiment Station Technical Bulletin 93.

Leone, G., Lindner, J.L., van der Meer, F.A., Scheon, C. D., and Jongedijk, G. 1998. Symptoms on apple and pear indicators after back transmission from Nicotiana occidentalis confirm the identity of Apple stem pitting virus with Pear vein yellows virus. Acta Horticulturae 472: 61-65.
Content edited by: Jay W. Pscheidt on January 1, 2009
 
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