FOREST PROTECTION 129 



Shortened growing season; 



Restricted number of species locally producible; 

 Double rings of wood, and possibly windshakes 

 in wood; 



Weakened condition of a tree, subjecting it to 

 insects and fungi, and also to breakage by 

 storm, snow and sleet, owing to the reduced 

 elasticity of the fibre. 



(c) Species afflicted: 



The species known to suffer, in one way or an- 

 other, from frost are called " sensitive;' ' the 

 others are known as "hardy" species. 



HARDY SENSITIVE 



AT BlLTMORE 



Chestnut Beech 



Maples Oaks 



Black Gum Catalpa 



Scotch Pine Oregon Ash 



White Pine Oregon Maple 



Rigid Pine Box Elder 



Halesia Pinus ponderosa 



Cottonwood Pinus lambertiana 



Hickories Pinus echinata 



Spruees Edgeworthia 



Douglasia Walnut 



Yellow Poplar Buckeye 



(d) The remedies against frost are almost entirely 



PREVENTIVE : 



(Restrictive measures are possible only in nur- 

 series, and consist in watering the beds after 

 very cold nights). 



I. IN NURSERIES* 



Late planting of seeds in spring, where late frost 

 is dreaded; or else early planting where early 

 frost is feared in fall; 



Lath screens, or nursery under cover (unless 

 lignification is handicapped); 



Clouds of smoke on frosty mornings; 



Avoidance of east aspects; 



Heeling-out transplants, so as to retard sprout- 

 ing in springy 



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