Pear psylla: In abandoned orchards

Abandoned orchards studied during the 1962 season showed substantial variation in their ability to support heavy populations of the pear psylla. There were indications that trees abandoned for several years may have arrived at a point where biological control factors will control the densities of this pest. The removal of single trees or of entire orchards that had been in this neglected state for several years is, therefore, of questionable value. However, in those orchards left unsprayed for only one or two years, psylla populations did reach high densities. Under these high summer population levels, several psylla adults were captured on traps placed considerable distances from the orchard. This greatly increases the danger from abandoned orchards in the adequate control of this pest in commercial plantings.