!N^Ew York Agricultural Experiment Station. 339 



generally known it will be found in many of the apple growing 

 sections of the northern, central, and l^ew England states. 



APPEARAE'CE OF CAm^ERED LIMBS. 



When one approaches a diseased tree his attention will be 

 attracted to the dark and enlarged sections of the larger limbs. 

 A closer exa^nination shows that the bark is much roughened as 

 well as thickened, and in many instances a portion of the wood is 

 laid bare. The decaying bark and wood offer a convenient lodg- 

 ing place for borers and fungi which aggravate the injury and add 

 to its unsightly appearance. The dead bark on many of the 

 diseased limbs clings tenaciously to the decaying wood, which 

 is a feature that distinguishes this canker from sun scald, since 

 with the latter trouble usually the first symptom to be noticed is 

 the peeling of the bark from the injured surface. The area of 

 bare wood is often small as compared to the extent of swollen 

 bark; limbs are frequently seen that for six feet or more of their 

 length are covered with rough bark. The progress of the disease 

 on such limbs may be marked by numerous pits or scars, show- 

 ing where the fungus was able to live until perchance it gained 

 entrance to the cambium through some injury, when a serious 

 wound was the result. These scars are usually circular in form 

 and may be outlined by two or more concentric lines. An exam- 

 ple of this form of the disease is shown in Fig. 1 of Plate XXIX, 

 where for more than six feet of its length the limb is covered with 

 tbe rough bark or the scars where the bark has become detached. 

 The fungus has only reached the cambium and formed a canker 

 at a. Fig. 2 of Plate XXX is a larger view of a section of the 

 same limb showing the scars more in detail. 



Other instances occur, where, though the bark is much swollen 

 and roughened, the fungus has not been abfe to penetrate to the 

 cambium, but has died after a time leaving the scars of its attack, 

 aside from which the limb has regained its normal condition. 



The fungus shows a preference for the larger limbs of mature 

 trees. Small limbs and young trees are much less frequently 



