J!^EW YoKK Agricultueal Expekimeist Station. 293 



there were dead spots as deep as the wood. Cork layers had de- 

 limited the dead from the living parts of bark. 



Small patches of internally injured bark were also found in some 

 crotches of this and various other trees in the same orchard. Many 

 of the upright shoots which so commonly originate from the larger 

 branches on closely pruned trees, also had the phloem more or less 

 disorganized and the wood slightly stained about their bases, although 

 no trace of the injury could be detected before most of the cortex 

 had been removed. The histological features of such injuries and 

 the changes occurring in them during spring are very interesting and 

 ■will be discussed in another paper. 



Further observations in a Weedsport orchard. — When seen again 

 on July 23, 1912, the injured Baldwin trees in the Weedsport orchard 

 described on page 265, and even those which had appeared unin- 

 jured, had not grown very well. They all looked decidedly scrubby and 

 stunted. Only a few of the sprouted stumps had been left and sev- 

 eral of them had been " winter-killed." Nearly all of the stumps 

 had been replaced by new trees which seemed to be growing nicely. 

 The Ben Davis trees, however, had grown remarkably well, as may 

 be seen in figure B on Plate XIII which is taken down a diagonal row 

 where all the Baldwin stumps had been replaced by new trees. 



Since the injured Baldwin trees had not grown at a normal rate the 

 callus growths were also smaller and had made less progress in the 

 process of covering the exposed wood. No additional injuries had 

 apparently occurred in the callus growths of trees injured in winter 

 of 1910-11, nor was any found on other trees of either the Baldwin 

 or Ben Davis varieties. 



GENERAL CONSIDERATIONS AND DISCUSSION. 



THE CAUSES OF CROWN-ROT. 



Introductory. — Although the foregoing observations go to show 

 that initial injuries which eventually result in crown-rot and canker 

 occur in winter, and that certain environmental factors and condi- 

 tions of trees at the close of a vegetative season are in some way re- 

 lated to the occurrence of the diseases, they afford only circum- 

 stantial evidence as to the factors or forces actually causing the 

 injuries and the disintegration and rot which follow. 



The bark of trees may be injured artificially in various and sundry 

 ways and still give rise to results that may be very similar to each 

 other and to some occurring in nature, but that after all can only be 

 suggestive. If the factors of the environment are not thoroughly 

 studied and sifted to assist in the selection of the causal ones, the sig- 

 nificant factors actually operative in nature in the production of a 

 disease under consideration may be overlooked. In an endeavor to 

 explain the natural phenomena by means of an agent assumed to be 

 the cause, similar results may often be artificially secured. For 



