North American Fruit Explorers mailing list at ibiblio

[Scott Smith <scott@cs.jhu.edu>]

Doug, I have also heard something to this effect (I forget the exact  
reason now).  I wanted to add that I have not sprayed my pears other  
than a dormant spray, but have still had the occasional outbreak of  
psylla in spite of that.  It has generally been localized to a few  
trees and has not been a problem every year.  So perhaps lack of  
spraying turns a major pest into a minor pest.

Scott

> I have read that pear psylla as a pest is largely an artifact of
> spraying, and I have seen and heard of several Pyrus communis pear  
> trees
> locally which yield good fruit without spraying. It may take a while  
> for
> the predator complex to become re-established. There are many Kieffer
> pear trees on boulevards  (Vineland fine sandy loam) in north St.
> Catharines, left over from commercial orchards when suburbia came in a
> few decades ago, which seem unbothered by pests.