16 BULLETIN 1264, U. S. DEPARTMENT OP AGRICULTURE. 



In every case but the last 2-1 stock shows the best survival. 

 Averaging all these results, it appears that if the survival of 2-1 

 stock is made the standard with a value of 100 for convenience, the 

 survival of 2-0 stock will be 62, 2-2 stock 52, and 1-2 stock nearly 

 the same, while 3-0, much poorer, is 16, and 1-1, poorest of all, with 

 a value of 14. The cause of this difference is the better balance 

 between the top and root in 2-1 stock than in any other. The tops 

 are small and the root system large and fibrous. That this is the 

 true explanation of the superiority is indicated not only by the data 

 in Tables 7 and 8, but also by the experience gained in planting 

 trees of different relative development but all belonging to the 2-1 

 age class. 



In the spring of 1916 a record of one thousand 2-1 trees planted 

 on five different sites was made, classifying both roots and tops as 

 large, medium, and small. The results were as follows at the end 

 of the first year: 



Trees with large top and large root showed a 75 per cent survival; 

 medium top and large root, 74 per cent; medium top and medium 

 root, 63 per cent; small top and medium root, 59 per cent; small 

 top and small root, 51 per cent; large top and medium root, 49 per 

 cent; medium top and small root, 48 per cent; and large top and small 

 root, 27 per cent. 



After considering all of the factors involved in the determination 

 of the age class of western yellow pine best adapted to the planting 

 needs of the region, the evidence is unmistakably in favor of 2-1 

 stock, from the standpoints of the relative balance between top and 

 root, the development of a compact fibrous system of absorbing 

 rootlets, and the ultimate survival and subsequent development in 

 the field. 



Season of planting. — The period from 1911 to 1913 saw consider- 

 able fall planting on a rather large scale. In addition to western 

 3^ellow pine, Douglas fir, Engelmann spruce, and a few exotic species 

 were rather extensively planted; but the results were so unsatisfac- 

 tory with regard to the species other than western yellow pine that the 

 practice was discontinued in favor of spring planting. Fall planting 

 of western yellow pine proved advantageous on southern exposures 

 where the snow melts very early, because it enabled the trees to 

 become established early in the spring while the nursery from which 

 stock could be supplied was still under snow. However, the greater 

 possibility of inclement weather accompanied by snows render all 

 fall planting projects uncertain. Experiments were continued until 

 the spring of 1920, the results of which are included in Table 10. 



In comparing the 100-tree plots planted in the fall of 1915 with 

 those planted in the spring of 1916 in Big Cottonwood Canyon, it 

 will be seen that the former show the highest percentage of living 

 trees and compare favorably in percentage of vigorous trees. On 

 the Ephraim Canyon watershed all fall plantings were very unsuc- 

 cessful; but it should be noted that none were made on open south 

 slopes similar to those in Cottonwood Canyon. On the other hand, 

 a comparison of the plantations established in the fall of 1919 with 

 those planted the previous spring or in the spring of 1920 shows that, 

 in practically every case, the spring plantings were superior to those 

 made in the Call. 



