Downy Chess Grass as a Host of the Pear Psylla

Extract

Pear and quince are primary hosts of the pear psylla, Psylla pyricola Foerster (Smith, 1941; Wilde, 1962), but the scarcity of quince in the Okanagan Valley of British Columbia eliminates it as an important host in that area.

In 1962 suspicious chlorotic streaking, symptomatic of feeding by sucking insects, was seen on downy chess grass, Bromus tectorum L., growing in two pear orchards heavily infested with pear psylla. As a result, greenhouse and field trials were conducted to ascertain if pear psylla, on occasion, feeds on this grass and causes phytotoxic symptoms. Cages, enclosing small, potted Anjou pear trees and clumps of downy chess grass growing around the base of these trees, were used in the greenhouse for confining 30 adult pear psyllids. An equal number of potted trees and clumps of grass were maintained under the same greenhouse conditions but without adult psyllids. Observations on feeding and phytotoxic symptoms produced in downy chess grass by the pear psylla were made between July 12 and October 19.