PROPAGATION OF WHITE PINE 3 



them, white pine in the present state of our knowledge is more difficult. But 

 within recent years, especially since the coming into use of root-inducing sub- 

 stances such as indolebutyric acid, much has been learned about the propagation 

 of white pine by cuttings and some of the principal results obtained by the writer 

 and others are here brought together. 



The material which follows is presented in the natural order in which a propa- 

 gator would normally proceed, beginning with some consideration of the source 

 of cuttings, ending with a description of the. growth of the cuttings subsequent 

 to rooting; and the methods employed are discussed in that order. 



Effect of Age of Trees from which Cuttings are Taken 



Cuttings of white pine used by the writer were obtained from trees twenty to 

 thirty years old, a point to be considered, for age of the parent tree is an important 

 factor affecting rooting. 



Cuttings of white pine and many other kinds of trees, e.g., species of spruce, 

 hemlock, apple, cherry, maple, oak, and ash, are known to root better if taken 

 from young, seedling, trees rather than from mature, adult, trees (5). 



White pine cuttings rooted readily if taken from young trees, three (26), four 

 (3), or six 3'ears old (4), but they usually root much less well if taken from older 

 trees. Thus in certain experiments in which cuttings from j'ounger white pines 

 footed satisfactorily, cuttings from trees more than ten years old (26) or from 

 trees twenty years old (3, 22) rooted poorly or not at all, 



There is some evidence that cuttings of other species of pine are similarly 

 affected by the age of the parent, for cuttings of slash pine (P. Caribaea Morelet) 

 rooted much better if taken from younger rather than from older trees""(19); 

 and cuttings of Monterey pine (P. radiata Don) which rooted well were obtained 

 from young trees (9, 12). 



There is, however, considerable difference in rooting response of cuttings of 

 white pine from different trees of the same age, and cuttings from older pines 

 have been rooted. There was fairly good rooting of cuttings from trees fifteen 

 years old (4, 22), from a tree thirty years old (6), and from one older tree (3); 

 and there was good rooting of cuttings from some trees twenty to thirty years 

 old in the work here described. 



However, other things being equal, better results may be expected if the 

 cuttings are taken from young trees, and it would probably be well to take cut- 

 tings from trees as early in the life of the tree as its desirable qualities become 

 evident. 



If the source of the cuttings is a tree which itself was grown from a cutting, 

 such a tree is not necessarily to be considered young merely because it grew from 

 a cutting which was recently rooted. A plant vegetatively propagated is only 

 part of an older plant although in another clonal generation and it is not biolo- 

 gically 3'oung in the same sense that a seedling is. But some trees like some men 

 may, perhaps, remain young longer than others, a possibility which is further 

 considered below in connection with clonal differences. 



Time of Year at which Cuttings are Taken 



Late winter is a good time of year to take cuttings of white pine, assuming, of 

 course, that the propagator has the needed greenhouse facilities. 



There was good rooting of cuttings taken here in March (6) and, in work else- 

 where, cuttings taken in February or in late or mid-winter rooted better than 

 did those which were taken at other tim.es of year (3). The dates named in the 

 tables which follow, all between January 6 and March 22, in the years 1941 to 



