PROPAGATION OF THE HIGH-BUSH BLUEBERRY 

 BY SOFTWOOD CUTTINGS 



By W. L. Doran, Research Professor of Botany, 

 and J. S. Bailey, Assistant Research Professor of Pomology 



The high-bush blueberry, Vaccinium corymbosum L., is usually propagated 

 by hardwood cuttings, a method described in some detail by Bailey et al. (t)*. 

 These cuttings root slowly, however, usually requiring about thirteen weeks at 

 least, and their rooting was not hastened or significantly improved by the root- 

 inducing substances with which Johnston (5) treated them. 



Less use has been made of softwood cuttings, although, even without chemical 

 treatment, they can be made to root well if not always very quickly. Principal 

 objects of the present work were to determine the effects of certain factors, i.e., 

 rooting media, treatment of cuttings, and stage of their growth when taken, not 

 only on total percentages rooting but also, and especially, on the time required 

 for the rooting of softwood cuttings. 



Relatively little investigational work has been done on the subject previously. 

 Hitchcock and Zimmerman (4) and Doran (3) found that the rooting of June 

 or July cuttings of several varieties of blueberry was improved or that they 

 rooted in larger percentages after treatment with indolebutyric acid, 20 to 40 

 milligrams or 50 milligrams per liter, but the time factor was not emphasized. 

 O'Rourke (6) concluded from the results of his work that the use of indolebutyric 

 acid in talc is justified with softwood cuttings of blueberry. Chandler and 

 Mason (2) observed no significant responses when they treated "summer" cut- 

 ings of several varieties with much lower concentrations of indoleacetic acid or 

 indolepropioriic acid. Percentages which rooted were increased by phenylacetic 

 acid but the investigators concluded that the results did not justify the recom- 

 mendation of a root-inducing substance for use with blueberry cuttings. 



In the work now to be described, cuttings of the variety Rubel were taken 

 three times in 1943: first on July 1 when the green berries were one-fourth to 

 three-eighths inch in diameter, again on July 8, and again on July 15 when the 

 first fruit to ripen was almost ready to be picked. All cuttings were made of 

 short side shoots, three to five inches long, with the basal cut at the base of the 

 current season's growth. 



The solution-immersion or powder-dip treatments with root-inducing sub- 

 stances were applied to cuttings in the usual way immediately before their in- 

 sertion in the rooting media. These were either sand or a mixture of equal parts 

 of sand and sphagnum peat. Both were in a glass-covered case in a shaded 

 greenhouse. Cuttings were watered daily, ventilation of the case was kept at a 

 minimum, and temperatures of the rooting media were usually between 70° and 

 90°F, 



In order to determine the effects of the several factors on rapidity of rooting 

 as well as on total percentages rooting, cuttings were examined weekly. Results 

 are recorded in Tables 1, 2, and 3. Treatments which failed to hasten or improve 

 rooting or root growth and treatments which caused injury are not listed in the 

 tables but they are discussed below. 



In general, cuttings rooted more rapidly and responded more to treatments 

 if they were taken July 1 than if they were taken later. Untreated cuttings in 

 sand-peat rooted 100 percent in 12 weeks when taken July 1, 48 percent in IS 



*N umbers in parentheses refer to literature cited. See page 8. 



