PROPAGATION OF TREES AND SHRUBS 35 



of the variety Poorman which were taken here in mid-July rooted 70 

 percent in sandy soil, 32 percent in sand. Late June cuttings of alpine 

 currant rooted 77 percent in 22 days after treatment with indolebutyric 

 acid (20 mg./l., 24 hr.), 39 percent witliout it (57). Rooting of October 

 cuttings of R. Grossularia was improved by treatment with naphthalene- 

 acetic acid (50 mg./l., 24 hr.) (113). 



Robinia Pscudoacacia, black locust, and its varieties can be propagated by 

 hardwood, winter and early spring, cuttings treated with indoleacetic acid 

 or naphthaleneacetic acid (100 mg./l., 24 hr.). Cuttings, six to twelve 

 inches long and about one half inch in diameter, were allowed to callus 

 for seven to ten days in moist sphagnum moss at 68° to 80" F. before 

 treatment. Stored in moist sand at 70° F. for about ten days following the 

 treatment, the}' rooted, in soil, more than 60 percent in the field, more 

 than 90 percent in a greenhouse (99). 



Rosa, rose. Most hardy climbing roses and hybrids of R. mgosa, some 

 hybrid teas, and some hybrid perpetuals do well on their own roots (121, 

 122). Cuttings of some species are difficult to root (10), but hybrid per- 

 petuals, Polyantha roses, most hardy climbers, and some hj'brid teas can 

 be propagated by dormant, late fall or winter, cuttings planted imme- 

 diately in a cold frame or stored cool, in sand, during winter and planted 

 outside in spring (122). Rose cuttings are taken in late fall in England, 

 and untreated October cuttings of R. rugosa there rooted to the extent of 

 100 percent (10). 



Greenhouse varieties of hybrid teas were most responsive to treatment 

 if cuttings were taken from canes of flowering wood just after petals 

 began to fall, and softwood cuttings rooted best if taken from garden 

 varieties of hybrid teas in August or from climbers and creepers in July 

 and August (62). Three buds are enough on a cutting (122). Sum- 

 mer cuttings of R. Hugonis, R. omeiensis, and prairie rose rooted better 

 if made with a heel (46) but all roses do not need one (121). There 

 was good rooting of three-node cuttings of hybrid teas made from 

 the basal portion of flowering shoots, the basal cut in the internode 

 below a node, the lowest leaf and the terminal leaflets of the remain- 

 ing leaves removed (62). Sand-peat, sand (62), and sandy soil (121, 

 122) have been used successfully as rooting media. Sandy soil gave 

 better results than sand with treated cuttings of a hybrid perpetual {27). 



Indolebutyric acid in very low concentrations (48) is the most effective 

 of the known root-inducing substances for rose cuttings and some of the 

 results of work with it as described by Kirkpatrick (62) are here sum- 

 marized. Cuttings of several, not all, garden varieties of hybrid teas, 

 taken in August from flowering shoots, rooted as much as 50 percent 

 more after treatment with 2.5 mg./l., 24 hr., or 2 mg./gm. talc. Similar 

 cuttings of greenhouse varieties rooted in 15 to 20 days after treatment 

 with 1.25 to 2.5 mg./l., 24 hr., or 1 to 2 mg./gm. talc. Rooting of summer 

 cuttings of several climbers and creepers, also R. multitlora, was improved 

 b}' 5 mg./l., 24 hr., or 2 mg./gm. talc but at least twice these concentra- 

 tions were needed to induce rooting of cuttings of R. Hugonis. Treatments 

 did not affect rooting of Pernettiana hybrids. Dormant cuttings of 

 R. multiftora responded to 5 to 10 mg./l.. 24 hr., or 2 mg./gm. talc if treated 

 cuttings were then given a temperature of 65° to 75° F., not lower. Air 

 temperatures of from 60° to 80° F. proved to be best for quick rooting of 

 rose cuttings in general and it was necessary to give them heat at other 

 times but not in summer. Indolebutyric acid had little effect at temper- 

 atures of less than 60° F. 



