Pome fruits--apple (Malus sylvestris Mill.), pear (Pyrus communis L.), and quince (Cydonia oblonga Mill.)--should be harvested at proper maturity, handled carefully, stored promptly, and cooled to the desired temperatures quickly if ripening processes are to be slowed and spoilage held to a minimum. Careful handling and refrigeration should be continued during transportation and marketing.
The word "disease" as used in this publication means any departure from the normal condition of fruits that detracts from their appearance, interferes with their usefulness, or reduces their value. Under such a broad definition the term disease includes abnormalities caused by fungi, viruses, functional or physiological disorders, and injuries such as mechanical, chemical, physical, and insect.
The common names of diseases used herein are for the most part those that have become well established in publications on plant diseases and that are in general use among persons concerned with the growing and marketing of apples, pears, and quinces. A few, such as Jonathan spot and York spot, include the name of the variety on which they were first described or on which they are most common. Some of the names such as bull's eye rot, flyspeck, and scald briefly describe the diseases to which they are applied. Still others contain the name of the causal or inducing agent; among these are alternaria rot and freezing injury.
A few of the names imply a quality of the affected tissues that is not really characteristic or typical, but the names are so well established by usage that it has seemed best to retain them. The diseased flesh of apples affected with bitter rot and bitter pit is not always bitter; black rot lesions are often only dark brown, and brown rot lesions eventually become black.
Most of the insect injuries are named for the insects that cause them.
The occurrence, importance, symptoms, cause, and control of diseases of pome fruits will be discussed under appropriate headings.
Market Diseases of Apples, Pears, and Quinces
(this book is currently out of print)
by Charles F. Pierson, research plant pathologist,
Michael J. Ceponis, research plant pathologist,
and Lacy P. McColloch, collaborator
Agriculture Handbook No. 376
Agricultural Research Service
United States Department of Agriculture, May 1971
(used with permission)