1 8 MAINi: AGRICUI^TURAL E^XPE^RIMieNT STATION. I909. 



observer — a business man who for the sake of out of door work 

 had spent all of his spare time for several years in giving this 

 orchard his personal attention and care — was confident that 

 nothing of this kind had appeared on any of the trees before. 



Whetzel has shown * that not only can injuries to the bark 

 and cambium which are usually called "sun scald" and "winter 

 injury" be caused by the pear blight organism Bacillus amylo- 

 vorus Burrill, but a crotch injury as well, which very closely 

 resembles that which is here figured and discussed. It was 

 thought at first that this was possibly the same trouble as he 

 described, but careful observation followed up for two seasons 

 leads to the conclusion that it is an entirely different trouble — 

 simply an unusual form of "winter injury" or "frost patch." 

 In this connection it should be remarked that the thousands of 

 apple trees in Maine which in the summer and fall of 1906 

 appeared perfectly healthy gave ample evidence in the spring 

 and summer of 1907 that winter- in jury or frost patches are very 

 real things and can occur independently of bacteria or fungi. t 



In addition to the reasons already given the following may be 

 ■cited as showing that probably adverse weather conditions and 

 not fungi or bacteria are the cause of the crotch injury in this 

 instance. Examination showed that crotch injury was almost 

 universally found in previously healthy orchards which in the 

 spring and summer fohowing the severe winter of 1906-07 

 showed a large percentage of dead or dying trees. It was very 

 common in hundreds of orchards where the injury was present 

 largely in the form of frost patches on the limbs or trunks, but 

 where there was every reason to believe the trees were perfectly 

 healthy the season before. Orchards owned by the University 

 and by Director Woods of the Station furnished excellent 

 opportunity for personal observation upon this point. These 

 had been given the best of care and attention. Both were in 

 very healthy condition up to this time. There is positive evi- 

 dence that there were no cankers, or dead areas on the limbs 

 or in the crotches of these trees, previous to the winter of 

 1906-7. Both orchards had a large per cent of trees killed out- 

 right and nearly all which were not killed were badly injured 



* Whetzel, H. H. Cornell Exp. Station, Bui. 236, 1906. 

 t See pages 12-17 of this bulletin. 



