This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
We cannot say that any varieties are free from attacks of this malady, or that any are less liable to it than others, though circumstances occasionally favor that belief. As a general thing, it is less fatal to slow-growing trees and varieties than to those of very rapid and rank growth.
A remarkable fact, and throwing some light (negatively,) on the pear blight, is the entire absence from this disease among the trees in the neighborhood of Boston. It seemed indeed strange to hear such men as the president and ex-president of the world-renowned Horticultural Society there, inquiring for the appearance and symptoms of the blight as of a disaster personally unknown to them, hut so universally known and dreaded in Western New York and in Ohio. Boston and Rochester are not dissimilar in temperature of climate, hence we cannot trace it satisfactorily or wholly to the weather. Nor is rapid growth a necessary cause, for more freely growing trees than the thousands on the grounds of M. P. Wilder, S. Walker, or C. M. Hovet, are nowhere to be found. A part of Col. Wilder's grounds consist of reclaimed bog. with an ample addition of improving and fertilising materials; and the finest pear grounds belonging to President Walker he stated had been very heavily dressed with yard manure, with additions of ashes and guano, and the whole repeatedly plowed, and repeatedly subsoiled, till mellow and rich in a high degree to a depth of about two feet. The growth of the trees fully corroborated his account.
Limited observations at Philadelphia indicated a somewhat similar condition of the trees at that place.