PROPAGATION OF TREES AND SHRUBS 29 



Picea glauca var. conica. Taken here in early December, cuttings in sand- 

 peat rooted 39 percent without treatment, 92 percent after treatment with 

 indolebutyric acid (70 mg./l., 20 hr.), with results less good in sand. Late 

 winter cuttings respond to treatment with 40 to 60 mg./l., 24 hr., or 2 to 

 12 mg./gm. talc, or, by the concentrated solution-dip method, 4 mg./cc. 

 (49). Cuttings are taken in summer in England (7). 



Picea Omorika, Serbian spruce. Suggested treatments with indolebutyric 

 acid are 40 to 80 mg./l., 24 hr., or 12 mg./gm. talc (61). 



Picea pungens, Colorado spruce. Best rooting was of cuttings taken in Feb- 

 ruary (61, 67, 127). Summer proved to be a poor time to take them (126). 

 April cuttings rooted 80 percent in 8 weeks after treatment with indole- 

 acetic acid (100 mg/L, 24 hr.), but bud development was retarded for a 

 few months following (109). Indolebutyric acid (40 to 80 mg./l., 24 hr., 

 or 12 mg./gm. talc) may also be used (61). Cuttings rooted better in 

 peat moss than in sand (44), but cuttings of the variety Kosteriana rooted 

 well in sand (66). 



Picea sitchensis, Sitka spruce. Late winter cuttings made of the current 

 year's wood rooted 100 percent in sand-peat in 60 days after treatment 

 with indolebutyric acid (25 mg./l., 24 hr.), less well if taken in fall or 

 early winter or if not treated (43). 



Pieris. P. japonica and P. Uoribunda can be propagated by cuttings taken in 

 July or August when the wood is nearly ripe, made with the basal cut about 

 one-fourth inch below a node (67), and inserted in sand-peat (80, 88). July 

 cuttings of P. japonica rooted 80 percent without treatment, 100 percent in 6 

 weeks with treatment (88). Indolebutyric acid (10 mg./l, 24 hr.) has 

 given good results with that species (61), which is also easily propagated 

 by leaf-bud cuttings taken in early summer (89). 



Pinus Strobus, white pine. Cuttings, treated or not (61), have not often 

 rooted well if obtained from mature trees or, in fact, from trees more 

 than three or four years old (24, 42, 109), but cuttings from older 

 trees can be rooted (24, 28, 74, 94). Cuttings which were taken 

 here in mid-March from a tree about thirty years old did not root without 

 treatment and rooted poorly or not at all, with or without treatment, if 

 taken from the upper part of the tree; but cuttings from the lower part of 

 the tree rooted 70 percent in sand-peat in 3 months after treatment with 

 indolebutyric acid (200 mg./l., 5 hr.) (28). 



Deuber (24) got 14 and 16 percent rooting of cuttings taken in December 

 and January from trees thirty years old, 30 percent rooting of cuttings 

 taken in February from a tree sixty years old; such cuttings rooting 

 better in sand than in sand-peat (1:1), better in the moist air of a green- 

 house at 70° F. than in a sweat bench at higher temperatures. Rooting was 

 somewhat improved by treatment for 24 hours with indolebutyric acid 

 (100 mg./l.), but improvement was not very great and this treatment was 

 sometimes injurious. He found that small cuttings, lateral twigs, root 

 better than large cuttings, terminal shoots, with all taken from the lower 

 part of the tree, and that winter, especially late winter, is apparently a 

 better time to take cuttings than spring, summer, or fall. 



Snow (94) took cuttings in August from trees ten years old and planted 

 them in outdoor beds, covered with sash at night, in a six-inch layer of 

 sand-peat over old horse manure. They were there carried through the 

 winter mulched with hay, rooting the following summer. There was 35 

 percent rooting of those which had been treated only with water, 47.5 

 percent rooting of those which had been treated with indolebutyric acid 



