136 Principles of Plant Culture. 



ture never- falls to the freezing point. But in localities 

 subject to frost, the liability of damage to vegetation 

 from this cause is governed more by cold air drainage 

 (209) and proximity to water than by latitude. It is 

 as important to select locations for peach growing with 

 reference to spring frosts in the Carolinas as in the 

 peach belt of Michigan, and favorable locations for the 

 apple in "Wisconsin sometimes escape damage from 

 spring frosts in seasons when the apple crop is cut off 

 by frost from extensive regions of the southern states. 



216. Methods of Preventing Injury by Frost. Any 

 non-conducting material lying between the earth and 

 space, whether spread directly upon the earth or at a 

 considerable height above it, acts as a blanket to inter- 

 cept the radiating heat, and thus prevents in a measure 

 the cooling of objects beneath it. For this reason, 

 straw, muslin or other non-conducting material spread 

 over plants, usually protects them from frost. 



While it is easy to protect a few plants from frost 

 by covering them directly, it is much more difficult to 

 protect large plantations in this manner. Considerable 

 plantings of the strawberry have been successfully pro- 

 tected from frost by covering the rows in the evening 

 with straw or marsh hay, and where these materials are 

 convenient, the work may often be cheaply and quickly 

 performed. 



The use of numerous small fires of oil or other com- 

 bustible material to raise the temperature above the 

 frost point has been recently adopted by western fruit 

 growers as a means of averting frosts. 



