92 



frosts occur, particularly if the night be calm. The dense cold air 

 flowing into the lowlands fills the hollows and cools vegetation to the 

 temperature of frost. In such places winterkilling is frequently 

 serious. A windbreak may also make a frost pocket even on a side 

 hill by interfering with the free circulation of air. 



In districts where injurious frosts occur, high elevations tipping 

 to the north or east where vegetation is rather backward in the spring 

 afford the best locations for fruit growing. Other locations compara- 

 tively exempt from injurious frosts are such as are near lakes or 

 large streams, which tend to produce an equable climate. (U. S. 

 E. S. B. 178.) 



Effect of Frost on Fruit Crops. The fruit grower, from time 

 immemorial, has been at the mercy of the elements. Frost is one 

 of the most formidable foes with which he has to contend. Millions 

 of dollars are lost annually by silent, relentless frosts that come either 

 when the trees are in blossom or just after the fruit has set. Recent 

 demonstrations in the fruit district of the Middle West have proved 

 beyond a peradventure that damage to fruit trees by frost can be con- 

 trolled to a greater or less extent. One of the fundamental principles 

 that underlie successful frost fighting is a knowledge of the subject 

 of air drainage. Cold air, like water, settles to the lowest ground, and 

 anything that will break up this stratum of cold air and cause it to 

 mix with the upper strata of warm air will prove of great value in 

 combating frost injury. Frost injury to fruit trees most frequently 

 occurs when there is a clear, still, dry atmosphere, and when the radi- 

 ation is uninterrupted by clouds or moisture, and the cold air settles 

 in poorly air-drained areas. While frosts may not be severe, they 

 are often just severe enough to damage the blossoms and tender 

 fruits, and they not only reduce a crop of fruit one-third to one-half 

 of what it should be, but sometimes destroy the entire crop for one 

 year or for several successive years. (Y. B. 1909.) 



Orchard Heating. In orchard heating the fuel to be depended 

 upon must be easy to light, a fuel that will burn a long time and that 

 will give out a great amount of heat ; it must also be easily controlled 

 in regard to temperature. Oil, in some form, doubtless best mqets 

 these requirements, but where oil is scarce and coal abundant tjje 

 latter would be the cheaper fuel. 



The oil heater, so far as we know, was first manufactured by a 

 firm in Fresno, Cal. Since then several styles of oil heaters have 

 been manufactured and put on the market. One of these well-known 

 and extensively used orchard oil heaters, constructed on scientific 

 principles, has a center-draft tube that feeds oil to the flames, pro- 

 motes combustion, and makes good use of the oil. The heater holds 

 about 5 quarts of oil, will burn six or seven hours, is made of 28- 

 gauge iron, and weighs, with cover, 1% pounds. It stands 11 inches 

 high. The heaters nest nicely, fitting one into the other, for ship- 

 ping purposes. The cover is made to fit like a lard-pail lid, and is 

 raised in the center so as to shed water. This heater has successfully 

 stood the test of several years. It is successful because based on the 

 principle that there is no need for great heat locally, but for numer- 



