ORCHARD PROTECTION. 73 



the past fev years have been located on the higher lands with 

 this factor prominently in view. To protect them against the 

 extreme cold, many of the groves on the lower lands are equip- 

 ped with wicker coal baskets, briquets of shavings, crude oil, 

 and asphaltum, or sheet-iron stoves in which the same material 

 is burned. Oil smudges (in tin receptacles) or other materials, 

 which are located at definite intervals in the spaces between 

 the trees, are sometimes burned. It is a common practice, also, 

 to run the water in the irrigation furrows between the trees on 

 cold nights, in order to make use of the latent heat in the water 



Fig-. 24. Form of smudger for use in protecting orchards from 

 frosts. It is used with a protected stone boat. 



as a means of frost protection. The materials employed in this 

 protection against frost injury are used to cause a circulation 

 of air over the grove in order to mix together the strata of differ- 

 ent temperatures or for the production of a cloud of smoke over 

 the grove in the morning in order to exclude the direct sunlight 

 and thereby prevent the rapid thawing of the fruit when it has 

 been frozen during the preceding night. It is the rapid thawing, 

 rather than the freezing, of the tissues, that causes most of 

 the injury to citrus fruits that have been subjected to ordinary 

 frost temperatures. 



