34 STATE BOARD OP FORESTRY. 



ECONOMIC PLANTING. 



Windbreaks. The protection afforded by windbreaks must be reck- 

 oned an important factor in the horticultural development of California. 

 The necessity of windbreak protection in many sections of the State 

 is so great that without it certain crops can not be raised. Many trees 

 are suitable for windbreak planting, yet California farmers are united 

 in the opinion that Monterey cypress is the only competitor of blue gum 

 and other eucalypts for this purpose. 



The eucalypts excel other species in their towering height and rapid 

 growth, thus affording a protection most quickly. The trees are slender 

 and open-crowned, but double rows of trees or close planting provide a 

 strong check against the wind. The blue gum surpasses all others for 

 this purpose, and should be used throughout its thermal range. Its tall, 

 limber shafts yield before the wind and act as a cushion to deflect the 

 air currents upward over an orchard, while ordinary windbreak trees 

 form a solid wall on the leeward side of which the wind draws down 

 and forms eddies. 



In the open valleys of Southern California Eucalyptus windbreaks 

 have become a prominent feature of the landscape and their presence 

 is recognized as indispensable to successful orcharding. To their pro- 

 tection may be attributed in large measure the fine quality of the Cali- 

 fornia citrus crop, and in this way these trees return vast sums annually 

 to the State. In citrus sections, such as the Santa Paula, San Fernando, 

 San Bernardino, San Gabriel and Santa Ana valleys, windbreaks alone 

 render the production of citrus fruits profitable. In unprotected 

 orchards, nearly the entire crop is frequently blown from the 'trees, or 

 so scarred and bruised that the grade and market value are much 

 reduced. Orchard trees are even broken or partially defoliated during 

 severe storms. To avert this danger and improve the grade of fruits, 

 windbreak planting is being greatly extended even in old citrus sections. 



More extensive shelter-planting is advisable in many sections of the 

 State, notably in the Sacramento and San Joaquin valleys. Hitherto 

 windbreaks have been used chiefly to shelter citrus orchards, but now 

 they are coming into favor to shelter vineyards, deciduous orchards, 

 olives and walnuts. Much more extensive development may be attained 

 by their use in sections where strong or cold winds are felt. Along the 

 coast, shelter from sea winds is found to increase the yield of grain 

 crops. 



Eucalyptus windbreaks in some sections have changed the aspect of 

 the country and by moderating the winds have greatly improved the 

 climate. Waste, sandy, stretches have been turned to productive 

 agricultural use. In the region of Oxnard the towering windbreak 

 lines hold the loose sand from drifting before the steady sea winds, and 



