124 Principles of Plant Culture. 



199. Low Plants are often Destroyed by Ice, especially 

 when the ice layer forms in direct contact with the soil 

 about them and remains for a time after the return of 

 warm weather. The same result is sometimes produced 

 by a covering of snow, of which the top has formed into 

 a crust of ice. Winter grain and strawberry plants are 

 often smothered in this way. Surface drainage of ground 

 devoted to such crops is highly important. 



SECTION II. METHODS OF AVERTING INJURY BY COLI> 



A DURING THE DORMANT PERIOD 



a By Treatment of the Soil. 



200. A Dry Soil Favors Wood Maturity, while an abun- 

 dant water supply retards it. Soil treatment that restricts 

 the water supply toward the close of the growing period 

 tends, therefore, to hasten wood maturity and thus to 

 reduce damage from cold (175). Tillage should be early 

 discontinued about trees liable to winter injury, and in 

 wet seasons, mulching should be removed. Oats, buck- 

 wheat or clover sown in the nursery or orchard in late 

 summer promotes wood maturity by increasing evapora- 

 tion from the soil and is further useful as a covering to 

 the ground in winter (196). Draining heavy or wet 

 soils promotes wood maturity by promptly removing sur- 

 plus water. 



b By Treatment of the Plant. 



201. Pinching the Terminal Buds (416 a) a few weeks 

 before the time for leaf fall favors wood maturity by 

 checking growth, as does the removal of the younger 

 leaves, in which food preparation is most active. These 



