PROPAGATION OF WHITE PINE 11 



6 hr.) rooted 43 percent in sand, 47 percent in sand-peat and only 12 percent in 

 sandy soil. 



In choosing between sand and a sand-peat mixture, one must remember 

 that peats are not all alike, nor are sands; and different rooting media may re- 

 quire somewhat different attention as, for example, in the matter of watering. 

 With this in mind, the propagator may need to do some experimenting with the 

 materials available to him. 



February cuttings of Pinus Mugo var. MugJius rooted slightly better in sand- 

 peat than in sand (28) but, in work elsewhere (14), treated cuttings of that pine 

 rooted well in coarse sand. And the most favorable environment for rooting 

 cuttings of slash pine included sand as the rooting medium (19). In the work of 

 one earlier investigator, sand gave better results than sand — peat (or peat) as a 

 rooting medium for cuttings of white pine (3). In the work of others (7) a mixture 

 of sand and peat gave better results than sand alone, but it is unlikely that they 

 were using the same sand or the same peat. 



Cuttings taken from three trees on January 12 and variously treated were set 

 in sand and in sand-sphagnum peat. Out of twelve possible comparisons in- 

 volving the same treatments, they rooted in higher percentages in the sand-peat 

 in six instances and in no case did they root markedly better in the sand. The 

 best rooting in sand-peat, 53 percent, was of cuttings which had been treated 

 with indolebutyric acid (200 mg./l., 6 hr.) followed by Hormodin No. 3. The best 

 rooting in sand was 29 percent. But cuttings taken another year on January 6 

 and treated with indolebutyric acid rooted 54 percent in sand, 34 percent in 

 sand-sphagnum peat, the latter lacking adequate drainage and probably having 

 at times a too high water content. That may happen also to sand if it is too fine 

 and a coarser sand is to be preferred. 



Cuttings taken from three trees on January 27 were variously treated and set 

 in either a sand-sphagnum peat mixture or a sand-sedge peat mixture. Out of 

 thirteen possible comparisons involving the same treatments, sand-sedge peat 

 gave the best results seven times and never did sand-sphagnum peat give better 

 results than did sand-sedge peat. Treated with indolebutyric acid, cuttings 

 from one tree rooted 16 percent in the former, 41 percent in the latter. Treated 

 with Hormodin No. 3, cuttings from another tree rooted 37 percent in sand-sedge 

 peat, 14 percent in sand-sphagnum peat, and cuttings from still another tree 

 rooted 34 percent in the latter, 53 percent in the former. 



These results are in agreement with those of earlier investigators (7, 8) who got 

 better rooting of cuttings of white pine in a mixture of sand and a well-decomposed 

 peat of sedge origin than they did in a mixture of sand and a European peat moss 

 of sphagnum origin. But sphagnum peats may differ, as may also sedge peats, 

 and the propagator can well make some comparisons of his own. 



In any case, a sand-peat mixture should not be allowed to become or to remain 

 too wet. Water should be applied lightly, although often, and there should be 

 some drainage material such as crushed rock below. Lacking such care, this 

 medium may give results no better than a moderately coarse sand if as good. 



Bottom heat in the bench is unnecessary for cuttings of white pine, in fact it 

 has been found to be undesirable (26). 



Atmospheric Conditions in the Propagating Room 



Although it is possible for the rooting medium to contain too much water, as 

 of course it is also possible for it to contain too little, there is small if any like- 

 lihood of the relative humidity over open benches in the greenhouse being too 

 high. An open bench gave better results than a closed propagating case or sweat 

 bench (3), but high relative humidity is essential if cuttings of pines are to live 



