During the Dormant Period. 127 



thus destroyed are dark-colored at the center. Often 

 only a part of the embryo flowers on a tree are 

 destroyed. 



197. Flowers are Especially Sensitive to Cold. Fruit 

 crops are usually wholly or in part cut off if a slight 

 frost occurs during bloom, and in certain fruits, as the 

 apricot and some species of the plum, the blossoms 

 sometimes appear to be destroyed by a degree of cold 

 that does not descend to the freezing point, possibly 

 through interference with pollination or pollen germi- 

 nation (150). When the freezing is accompanied with 

 snow, however, open flowers may escape without harm, 

 probably owing to the slow extraction of the frost 

 (189 b). 



198. Low Plants are often Destroyed by Ice, espe- 

 cially 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 effect results some- 

 times from a covering of snow, of which the top has 

 formed into a crust of ice. Winter grain, strawberry 

 plants and lawn grass are often smothered in this way. 

 Surface drainage of ground devoted to such crops is 

 highly important. 



Section II. Methods of Averting Injury by Cold. 

 A — During the Dormant Peeiod. 

 a — By Treatment df the Soil. 



199. A Dry Soil Favors Wood Maturity, while an 

 abundant water supply retards it. Soil treatment that 

 restricts the water supply toward the close of the grow- 



