94 HORTirFLTTRAL MANUAL. 



most other orchard fruits. As the years go on it is found 

 that the hill orchards in Michigan, Georgia, Missouri, 

 Iowa, and indeed about all the States, are most productive, 

 the trees most perfect, and the fruit commands best prices 

 in market. The superior adaptation of orchard fruits to 

 such sites do not all arise from free air-circulation and the 

 descent of frosts, fogs, and vapors to lower levels. The 

 mechanical condition and color of the soil have usually 

 something to do with it and relative exemption from frost 

 is not the least advantage in the blossoming period. In 

 the prairie States a ridge only ten feet above the general 

 level usually escapes ruinous frosts when the blossoms on 

 the general level are killed. During still nights, when 

 frosts at this season are most to be feared, an elevation 

 of only ten feet on the prairies will show a temperature 

 several degrees higher than, the level where the cold air 

 settles. 



98. North and South Slopes. In our relatively sunny 

 and hot sections where dent corn ripens, and melons can 

 be perfected in the open air, the direction of the slope is 

 more important than in cooler and more humid climates. 

 The temperate-zone orchard fruits will not endure without 

 injury such heated soil and air as the grape or melon, 

 hence the talk about cover-crops to cool the soil and north 

 slopes to avoid the direct rays of the sun. In the dent- 

 corn belts of the prairie States in the early days, the north 

 slopes of ridges and drift moraines had thrifty thickets of 

 wild plum, crab-apple, gooseberry, wild currant, and other 

 ligneous growth never found on the south slopes. In like 

 manner we now find our thriftiest and best bearing 

 orchards of apple, pear, plum, and cherry on the north 

 slopes. This is specially true of the bluff areas near our 

 streams where the north slopes are more decided. 



Yet to a large extent this is a subject for local study. 



