ANNUAL REPORT, 1941 75 



DEPARTMENT OF HORTICULTURE 

 R. A. Van Meter in Charge 

 Propagation of Hemlock. (Harold S. Tiffany, Waltham.) 



Canadian Hemlock, Tsuga canadensis. Cuttings of one-year wood were taken 

 from hedge trees approximately fifteen years old, in three series at five- week 

 intervals: December 9-14, 1940; January 13 18, and February 17-21, 1941. 

 The rooting medium was one-third peat and two-thirds sand, in open benches 

 under cheesecloth tents and whitewashed glass. Cuttings were kept fairly moist. 

 All treatments were run at constant temperatures of 65°, 70°, and 75° F. (main- 

 tained by electric cable), as well as in an unheated bench where the temperature 

 averaged about 60°. Each lot consisted of six cuttings. 



Immersion treatments consisted of honey, 25 and 50 percent solutions for 24 

 hours; indolebutyric acid in the form of Hormodin A, at concentrations of 30 

 45, 60, 75, 90 BTI units for 24 hours (with additional treatments at certain tem- 

 peratures); indolebutyric, indcleacetic, and naphthaleneacetic acids, each at 

 concentrations of 7^, 10, 12)^, 15, 20, 30, 40, and 50 mg./lOO c. c. water for 

 24 hours (with additional tests for 16 and 40 hours); Roche 202, at 50, 100 200 

 unit solutions for 24 hours. Powder treatments consisted of Formula No. 66 

 and Hormodin Powders Nos. 2 and 3. An untreated or check lot was included. 



Untreated lots rooted little or not at all: at 60° F., 16 percent; at 65°, 33 percent- 

 at 70°, 16 percent; and at 75°, none. Rooted cuttings of successful lots could have 

 been potted at ten to twelve weeks. 



Outstandingly rapid rooting, as compared with other treatments, was shown 

 by Hormodin A, 30 BTI units for 24 hours at 75° F. This reaction checked 

 similar findings of the previous season (Hormodin A, 45 BTI units for 24 hours). 

 See photograph page 56. 



Cuttings from Series I, taken in early December, gave much higher percentages 

 of rooting than those of Series II or HI. In the previous year mid-December 

 cuttings did not root as successfully as those taken in mid-January. This variabili- 

 ty can be at least partially explained by the early low temperature and snow fall 

 of November 1940 which brought the cuttings to a condition for satisfactory 

 rooting much earlier than was the case in the preceding year when such condi- 

 tions did not materialize until January. 



Of the thirty-one treatments which gave 100 percent rooting, the most con- 

 sistently successful was indolebutyric acid 73^ mg./lOO c. c. for 24 hours. The 

 finest normal root systems were developed with this treatment at 65° F. (see 

 photograph, page 56), with good rooting at 70° and 60°. Of economic signifi- 

 cance is the fact that this treatment gave 83 percent good rooting in the unheated 

 bench at an average temperature of 60° (widest fluctuations in the bench tem- 

 perature were 57° and 63°). Consistency of the treatment at 65° is further shown 

 by 100 percent rooting from 73^ mg. upward through 40 mg., although as the 

 concentration increased the roots were shorter and some injury was apparent. 



Hormodin A trials were consistently good with percentages of 100 on half the 

 lots. Best-developed root systems were from 90 BTI units, 24 hours at 65° F. 

 As would be expected, lower concentrations did best at higher temperatures and 

 vice versa. This was shown particularly well by the best 100 percent rootings 

 in the Hormodin A, 24-hour trials: 30 BTI at 75°, 60 BTI at 70°, 90 BTI at 65° 

 and 60° F. 



Cuttings treated with indoleacetic acid gave 100 percent rooting at 60° and 

 65° F. with concentrations up to 10 mg./lOO c. c. In no instance did the condition 

 of the roots excel or equal the condition of those treated with indolebutyric acid. 



All naphthaleneacetic acid treatments gave indication of injury by basal burn 



