92 The Principles of Fruit-growing. 



are useful. A mixed plantation, with the hardiest 

 and most vigorous deciduous trees on the windward, 

 is probably the ideal artificial shelter belt.* 



PROTECTING PLANTATIONS PROM FROST. 



Having now considered the relations of location, 

 site and wind-breaks to cold and frost, we may ad- 

 dress ourselves to a discussion of the means by which 

 injury from local frosts may be averted, in case they 

 threaten to occur. These means are of two types, 

 those which attempt to enable the plant to escape 

 injury from the frosts, and those which attempt to 

 prevent the frost from occurring. Altogether there 

 are six general means which have been proposed for 

 protecting plants from frost: Mulching, covering the 

 plants, adding the vapor of water to the atmosphere, 

 making artificial clouds, causing currents of air, and 

 heating the air.f 



Middling to enable plants to escape frost. % It is 

 a general opinion that a mulch or heavy cover placed 

 upon the soil about plants when it is frozen will re- 

 tard flowering and the maturing of fruit ; yet the 

 practice appears to be often unsatisfactory, and there 

 are reasons for supposing that the philosophy of the 

 subject is not commonly understood. The subject is 

 one of increasing importance, for it is essential that 



*Bnll. 48, Neb. Exp. Sta., on wind-breaks, comes to hand as we go to press. 

 tA seventh category may be added, whitewashing the plants. See Whittei. 

 Bull. 38, Mo. Exp. Sta., and Garden-Making, p. 64. 

 {Consult Bull. 59, Cornell Exp. Sta. 



