Abstract:
The pear scab fungus (Venturia pyrina Aderh.) has been in
Oregon for many years. It has become a serious economic problem
in the main pear-growing districts since 1932. Of all diseases, scab
causes the most consistent depreciation of Oregon's 6-million-box
pear crop, although pear blight may be more spectacular during occasional
seasons of epidemics. During seasons favorable for scab
infestations, losses of 20 to 30 per cent of the fruit have not been uncommon,
and where control practices have been neglected the losses
often reach 80 to 90 per cent in individual orchards. Pear scab is
common in western Oregon, occasionally severe in the Hood River
and Rogue River valleys, but is rare in the drier districts of eastern
Oregon.
Studies were started in 1932 to develop satisfactory control
measures for pear scab, particularly for the tender-skinned varieties
which were subject to injury by the fungicides in general use at that
time.
