PROPAGATION OF WHITE PINE 7 



related to the factor of light; and, as has already been pointed out, cuttings from 

 the lower branches, often niore shaded, usually root better than do those from the 

 upper. 



Since there is usually little if anj' rooting of untreated cuttings from older 

 trees and since cuttings from different trees differ in their response to root-in- 

 ducing substances, the propagation of white pines by cuttings will have to be 

 confined for the present to those individuals the cuttings of which do respond. 



If, however, cuttings from a desirable individual fail to root at all well one year, 

 they should be given another trial the next. Cuttings taken from the same tree 

 sometimes rooted better one year than another. The converse may be true also, 

 cuttings from the same tree sometimes rooting less well than in the previous 

 year (4). 



Treatments of Cuttings with Root-inducing Substances 



Cuttings of several species of pine are known to respond to treatment with 

 root-inducing substances. Treatments with solutions of indolebutyric acid 

 improved the rooting of cuttings of slash pine (20), lace-bark pine, P. Biingeana 

 Zucc. (13), and two varieties of mountain pine, P. Miigo Turra (13) (28). Root- 

 ing of cuttings of lace-bark pine and a variety of mountain pine was also improved 

 by indolebutyric acid applied in powder-dip treatments (13). Treatment of 

 cuttings of western yellow pine, P. ponderosa Laws., with indolebutyric acid gave 

 fair results in one experiment, inconclusive results in another (18). Cuttings of 

 slash pine responded to treatments with a solution containing indolebutyric, 

 naphthaleneacetic and indoleacetic acids, vitamin Bi, mineral- elements, and 

 sugar (19). Cuttings of white pine treated with sucrose before treatment with 

 indolebutyric acid lived longer (6), but in more recent work here they rooted in 

 no larger percentages than did those treated with indolebutyric acid alone. 



Results of earlier investigators with cuttings of white pine and root-inducing 

 substances are not wholly consistent or in complete agreement and, considering 

 the many factors involved, that is not surprising. It appears, however, that 

 cuttings from young trees are more responsive to such treatments than are cut- 

 tings from older trees and that cuttings some of which root without treatment 

 are more likely to be benefited b}' treatment than cuttings which root less well 

 or not at all without treatment. Also, as has been pointed out, there is much 

 difference in the effects of the same treatments on cuttings from different trees. 



Treatments of cuttings of white pine with indoleacetic acid induce certain 

 anatomical and histological changes (2), but the rooting of cuttings from older 

 trees was not improved by indoleacetic acid applied in solution (26) or in talc (7) 

 and no use was made of this material here, most of the treatments about to be 

 described involving the use of indolebutyric acid instead. 



Cuttings taken in January from white pines twenty to forty years old rooted 

 only 6 percent without treatment, 26.6 percent after treatment with indolebutyric 

 acid 100 mg./l., 24 hours, although this treatment was injurious to some other 

 cuttings (3), perhaps because it was too long continued. Rooting of cuttings 

 taken in March was much improved by indolebutyric acid 200 mg./l. applied for 

 as short a time as five hours, and twenty hours was apparently too long at a 

 concentration of even 100 mg./l. (6). Rooting of March cuttings from a young 

 white pine was improved only half as much by a solution-immersion treatment 

 with naphthaleneacetic acid as by indolebutyric acid similarly used and at the 

 same dosage, a relatively low concentration, compared with that used by the 

 present writer, and indolebutyric acid in a powder carrier was also beneficial (4). 

 Hormodin No. 3 improved the rooting of cuttings from a young white pine (3). 

 Rooting of cuttings taken in August was somewhat better after treatment with a 



