ARBORICULTURE 



ARBORICULTURE 



361 



twenty pounds of nitrogen, per acre from the soil, for 

 continuously used nurseries the addition of mineral 

 materials in the shape of bone-meal and wood-ashes 

 may become desirable. 



A large number of seedlings may be grown in a small 

 space; thus 30,000 Norway spruce may be grown on a 

 square rod, requiring about two pounds of seed. The 

 quantity of seed sown depends, in part, upon the length 

 of time it is expected to leave seedlings in the seed-bed, 

 besides size and quality of .seed; the quantities vary 

 from one-fourth to one-half pound per 100 square 

 feet if sown in drills, and the yield of seedlings will 

 vary from 2,000 to 25,000 seedlings, according to species 

 and seasons. 



Transplanting and pruning. 



Conifers, like any other trees, may be transplanted at 

 any time of the year, provided the necessary care is 

 taken in moving the plant. This care is least required, 

 as with other trees, in the fall and early spring, when 

 activities of root and foliage are, if not at rest, at least 

 reduced. Which of these seasons is preferable depends 

 on the locality, and the dependent character of the sea- 

 son. On the" whole, spring planting will probably be 

 preferable in most parts of the United States which 

 do not suffer from dry spring winds. In localities of 

 the Southwest, which have commonly a dry spring 

 followed by a rainy season in July, this latter time 



322. An ideal shade tree. White oak. 



should be chosen. There is a belief that planting in 

 August is specially favorable. There is no reason 

 for this belief, unless favorable weather (a rainy season) 

 follows. 



Conifers may be transplanted later than deciduous 

 trees, even after the buds have started, excepting the 

 larch, which buds out very early; with this species, fall 

 planting may be recommended. Cloudy weather, rather 

 than rainy or very dry, should be chosen, especially 

 when transplanting into nursery rows. 



Young trees are naturally more readily and success- 

 fully transplanted than older ones, with which there is 

 more difficulty in securing the whole root-system when 

 taking them up. Since, however, the seedlings develop 

 slowly for the first one or two to three years, they should 

 be left in the seed-bed for that length of time, root- 

 pruned, and then transplanted into nursery rows. Al- 

 though those with a shallow root^system, like spruces 

 and firs, may be moved even when 30 to 40 feet in 

 height, it is best, even for ornamental purposes, not to 

 take them more than 3 to 4 feet in height. In forestry, 

 one- to four-year-old plants, according to species, from 

 2 to 12 or 15 inches in height, are preferred for reasons 

 of economy. 



Much greater care than with deciduous trees is 

 necessary, when transplanting without an earth-ball, in 

 keeping the root fibers from drying out; a large amount 

 of loss in transplanting is explained from neglect in 

 this respect. As soon as taken up, the roots should be 



323. Good street trees. Pin oaks. 



immersed into a loam-puddle, or kept protected by 

 wet sphagnum moss or canvas until set into their 

 new place. 



The question of trimming when transplanting must be 

 considered with more care than is necessary with broad- 

 leaved trees, which possess much greater recuperative ' 

 power. It should be confined to the smallest amount, 

 smoothing bruised roots, and if for proper proportion- 

 ing pruning at the top becomes absolutely necessary, 

 shortening the leader rather than branches. Larcb will 

 stand more severe pruning than most other conifers. 

 From the artistic as well as physiological point of view, 

 it is barbarism to remove the lower branches, which the 

 tree needs to shade its trunk and standing room, and 

 often, when deprived of the same, will replace first 

 before starting again, in its height growth. Attention 

 should, however, be especially paid to preventing dou- 

 ble leaders, which are detrimental to future form-devel- 

 opment; cut them out as early as possible, preferably 

 in the bud. Laterals may be somewhat shortened-in 

 while standing in the nursery, to lengthen the time 

 during which the lower branches are to persist. Break- 

 ing out buds is, as with all trees, the best method, pro- 

 vided the pruner has an eye for his business. Even in 

 after-life, when pruning is performed to keep the tree 

 shapely, the minimum use of the pruning-knife should 

 be the rule. 



There are three marked periods in the development of 

 conifers the juvenile period, when the entire tree is a 

 crown, branched symmetrically to the base, the perfec- 

 tion of symmetry; then follows the adolescent stage, 

 when the lower branches die out, a period of unshape- 

 liness; followed by the virile stage, when the straight, 

 cylindrical shaft bears the crown at one-third or one- 

 half of the upper length of the bole. The trimming 

 during the adolescent stage requires most considera- 

 tion. It is, in most cases, best to take off only the 

 lowest, dying or dead branches, as it becomes necessary. 



In pruning, cut as closely as possible to the trunk, 



324. Effect of trees on city street compared with no trees. 



