The Western Yellow pine, Pinus ponderosa, and Scotch pine, P. sylveslria, 

 have been found to succeed quite well under irrigation in this locality! 

 Figure 3, (a) and (b). Evergreens of this character are difficult to start, 

 and grow much slower than the preferable deciduous species. On the other 

 hand, they are capable of withstanding wide extremes of climate and when 

 well established are more or less drought resistant. Their slow development 

 is more than offset by their superior value. They afford as effective protection 

 from cold winter winds as from drying winds in summer. An abundance of 

 dark green foliage renders them very attractive at all seasons. The three 

 most promising species are shown in Figure 4. 



A row of pines planted to the leeward of a windbreak or shelter belt will 

 be favored by the protection afforded it while young, and when mature will 

 take the place of the shorter-lived deciduous trees. 



Frequent occurrence of evergreens with their heavy foliage add greatly 

 to the attractiveness of a neighborhood, especially in winter. This is particu- 

 larly noticeable in arid regions where they are so infrequently found. 



In selecting other than the desirable species of trees named above for 

 use as windbreaks, considerable care should be exercised. Observations 

 should first be made about the country to find what kinds succeed best, and 

 from them the most desirable species should be chosen. If a tree not to be 

 found in the locality is desired, a study should be made to determine its size 

 and shape, its requirements of soil, and also what extremes of temperature 

 it will stand. 



Lack of attention to the value of trees often results in the planting of very 

 undesirable kinds. The silver-leaf poplar, Populus ni>ea, on account of its 

 habit of sending out numerous suckers from the roots, which spread over a 

 large area, should not be planted on other than waste land, and in out-of- 

 the-way places. The tree also has a disagreeable habit of shedding large 

 quantities of "cotton" in the fall of the year. This cottony-appearing material, 

 which is in the form of a small sail or float attached to the seed, enables it to 

 be carried through the air and scattered for long distances. Russian mul- 

 berry, Morus, Figure 4, Box Elder (cut-leaf maple), Acer negundo, Hardy 

 Catalpa, Catalpa sp., and Osage Orange, Toxylon pomiferum, are not thrifty 

 on this soil and make insufficient growth to be of value. 



Arrangement of Trees in the Windbreak. Careful study should be made of 

 the height and vigor of growth, and general success of trees to be used in a 

 windbreak to determine in what manner they should be placed to give the 

 best results. 



The manner of placing depends upon habit of growth of trees and the 

 number of rows that are to be planted. Spreading trees set five feet apart in 

 single rows make an effective shelter, as numerous strong branches closely 

 fill the intervening spaces. Slender trees should always be planted in two or 

 more parallel rows with the trees in one row opposite the spaces in the other. 

 These two types, the spreading and the slender, should never be planted 

 alternately in the same row. At some point in such a row one type usually 



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