15 



The use of undesirable species was frequently the cause of failure. 

 Such trees as black locust, chestnut, beech, and others which were 

 widely used, were total failures because of insect attacks or lack of 

 hardiness. 



PLANTING AND CARE OF WINDBREAKS. 



Species to be used. — A greater variety of trees has been planted 

 in the State for windbreaks than for any other purpose, but the 

 number which can be used successfully is limited. Certain species, 

 although not of the greatest usefulness for windbreak purposes 

 solely, have a high value for fuel, posts, and farm repair material. 

 These may be used to advantage both for windbreaks and the pro- 

 duction of wood supplies. The best of these ''dual purpose" trees 

 are included in the following list : 



Honey locust. Hardy catalpa. 



European larch. Russian olive. 



Silver maple. White willow. 



Cottonwood. Osage orange (in central and 

 Green ash. southern Iowa). 



The black or yellow locust would answer the two requirements 

 better than any of the trees mentioned but for its susceptibility to 

 the attacks of the locust borer, wliich riddles and kills it within a 

 few years. 



Some of the pines and spruces are much more valuable than smj of 

 the broadleafed trees for windbreak planting alone. They retain 

 their leaves throughout the year and thus provide protection during 

 the wdnter when it is most needed. The hardier evergreens may be 

 successfully grown under nearly all conditions of soil and moisture, 

 and their growth is often more rapid than that of the more permanent 

 hardwoods. Climatic and other conditions which influence tree 

 growth are more severe in the western part of the State than in the 

 eastern counties, and it has been found that certain of the Pacific 

 coast and Rocky Mountain conifers do better there than those from 

 the East. The evergreens recommended for planting in different parts 

 of the State are given in the following list : 



Eastern Iowa. Western loua. 



White pine. Black Hills spruce. 



White spruce. Western yellow pine. 



Norway spruce. Austrian pine. 



European larch. Scotch pine. 



Austrian pine. Douglas fir. 



Colorado blue spruce. • White pine. 



Arbor\dt8e. Colorado blue spruce. 



Hemlock. White fir. 



Scotch pine. European larch. 



White fir. Norway spruce. 

 Douglas fir. 



Western yellow or bull pine. 

 Tamarack. 

 [Cir. 154] 



