so 



space up and down the trunk the bark above ground may be frozen 

 solid, while just below it may be free from frost and vice versa. 



During high winds the twist and strain upon a young tree may 

 be severe at the surface of the soil, especially if the ground is 

 frozen. Fruit trees are commonly planted so that the point of bud- 

 ding is at or near the surface of the soil, and even though the 

 union between the top and the root be a most congenial one, never- 

 theless, it is the point where the freezing and thawing process is 

 most likely to find a weakness. 



It is not so remarkable then that fruit trees suffer considerably 

 from collar injuries, which commonly result in what is termed 

 collar rot. 



The actual decaying of the bark is secondary and is preceded by 

 winter injuries, which actually damage the bark. Such injuries are 

 quite common in New York State and our more northern fruit 

 sections, especially with varieties of apples, such as the King and 

 Gravenstein. 



Collar injury to apples is not common in New Jersey, but 

 much damage has occurred to peaches. Collar injury or collar rot, 

 if severe, results in the killing of a section of the bark completely 

 around the trunk, near the surface of the soil, while above and 

 below this point the bark of trunk and roots may be free from in- 

 jury. The tree is now girdled and will continue to live until the 

 stored up food, in the roots and top, is exhausted, when it will sud- 

 denly die. 



In less severe cases where only a portion of the bark is killed 

 the tree may continue in fruit bearing for several years. But un- 

 less given attention, the injury is likely to grow more severe each 

 year. Borers, bark beetles and other enemies add to its troubles and 

 the tree dies. 



Collar injuries which effect the bark, but not severe enough to 

 destroy it at first are quite common upon peach trees. The effect 

 of slight damage is usually first observed in a rolling and early 

 ripening of the leaves in the middle or latter part of the following 

 summer, and if not too severe the fruit will be forced up to a larger 

 size than upon normal trees in the same orchard. Such forced fruit 

 is sometimes slightly bitter, but in any case, it can always be de- 

 tected by its coloring. Minute white dots, even in the highest col- 

 ored specimens tell the story. Trees injured only to this extent are 

 likely to decline rapidly unless cut back and well cared for. 



The killing of fruit buds is a form of winter injury that is 

 better understood, generally, than some of the other forms of in- 

 jury, already mentioned, but the exact cause of the injury in each 

 case is not as easily determined as is sometimes supposed. 



Late fall growth with immaturity of buds, low winter tempera- 

 tures or a premature starting into growth during mild periods are 

 common causes widely accepted. Let me add to these above- 

 mentioned factors the poor development of fruit buds due to dry 

 and unfavorable soil and weather conditions, in summer and fall. 



