APPLE DISEASES 35 



FROST-INJURY 

 Caused by the action of low temperatures 



The remarks which follow apply for the most part to that 

 phase of frost-injury commonly known as winter-injury. Prop- 

 erly winter-injury includes injury to all parts of the tree caused 

 by low temperatures in the winter months. Some attention 

 will be given to injuries due to spring frosts, but the general 

 statements are made with a view to an explanation of the 

 important problem of winter-injury. Of all the phases of 

 frost-injury, sun-scald and crown-rot, or collar-rot, are most 

 prominent and will therefore receive proportionate attention. 

 Sun-scald is now regarded as a late form of winter-injury, 

 while crown-rot is an early form of winter-injury. The term 

 frost-injury is used broadly to include all injuries to fruit-trees 

 due to the action of low temperatures without regard to the 

 season of the year. 



For many years it has been commonly observed that most 

 fruit-trees suffer from the effects of severe cold and of sudden 

 and extreme temperature changes in the cooler seasons. 

 Authenticated records date back for a century and unquestion- 

 ably the trouble was as common then as it is now. Theories 

 were advanced immediately in earlier times to explain the 

 occurrence and action of frost, some of which are still promi- 

 nent, although each has been modified in some degree. All 

 kinds of fruits are injured at some time or other ; however, there 

 is noticeable difference among fruits in this respect. It is 

 generally accepted, for example, that while the apple is severely 

 injured by cold, the peach is the more susceptible. 



In the northeastern United States such apple-varieties as 

 the Ben Davis, Northern Spy, Baldwin, Rhode Island and 

 Tompkins King are all likely to suffer from cold. Others, such 

 as the Oldenburg, Grimes and Hubbardston, often exhibit 



