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MASS. EXPERIMENT STATION BULLETIN 190. 



ditions where other varieties gave low percentages of rooting trees, it is 

 probable that Bethel would, under more favorable conditions, give at 

 least a low percentage of rooted trees. Considering the number of va- 

 rieties tested it seems safe to say that any variety of the common apple 

 may be propagated on its own roots by the nurse-root method. 



There are fourteen varieties that have been propagated in consid- 

 erable numbers in successive years and under different conditions, so 

 that we may feel fairly certain that the percentage rooting is fairly rep- 

 resentative for these varieties under the general conditions in which 

 they have been grown. Arranged in order of percentage rooting they 

 are as follows : — 



Coming now to the question of why certain of these varieties root 

 better than others we find a rather difficult problem. We have made 

 few investigations aimed directly at this question, but some discussions 

 may be ventured. 



The property of rooting is not directly correlated with vigor. Tolman 

 is fully as strong growing a variety in the nursery as Bough. Further- 

 more, observations made on digging the trees fail to discover any noticeable 

 correlation between vigor and rooting. It has seemed to the writer that 

 a small, weak tree was as likely to be rooted from the scion as a strong 

 one. 



Some varieties branch more freely than others. During the season of 

 1916 a block of yearling whips branched quite freely from the newly formed 

 axillary buds. Notes taken at the time are as follows: No branches, 

 Northern Spy; few, Baldwin, Bough, Oldenburg, Tolman; all. Trans- 

 cendent (Crab). This gives no indication of any correlation between 

 rooting from the scion and branch growth from axillary buds. A more 

 reasonable expectation might be for a correlation between root formation 

 and branching from adventitious buds on the stem. No exact record of 

 branching from adventitious buds is available, but limited general ob- 

 servation of the behavior of budded trees leads the writer to believe that 

 such a correlation may exist, and that Bough and other free rooting 

 varieties do send out shoots from adventitious buds more freely than 

 Tolman and other varieties that root only sparingly. Further and more 

 definite records may prove or disprove this belief. 



The relation of callus formation in cuttings has been referred to. (See 

 page 75, Fig. 1.) Unfortunately no full notes of callus formation on 

 the cuttings set was kept, but it is suggestive to point out that Yellow 



