Pear scab in Oregon

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.