This section is from the book "Commercial Gardening Vol3", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
The account given under "Apple Scab" applies to Pear Scab, so far as the general appearance of the fungus and preventive methods are concerned. When the fruit is scabbed, deep, gaping cracks usually appear, whereas such cracks are not frequent on Apples. The same disease attacks the Crab, Hawthorn, and cultivated forms of Cotoneaster, from whence the disease may be conveyed to cultivated Apple and Pear trees. (See p. 84.) [g. m.]